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Linux 5.6 is the most exciting kernel in years

714 points by alexellisuk 7y ago

ficklepickle 7y ago
I'm really excited about the NFS client cache stuff. It's crazy that the whole system grinds to a near halt if it loses connection to the NFS server, from an end user perspective. I look forward to some time in the future when Debian incorporates this kernel. I prefer to use stock kernels. I used to enjoy messing with my distros, but these days I prefer stability.
- LeoPanthera 7y ago
  I’m not an NFS expert, and I’ve often wondered about client caching of NFS to improve performance. Does this exist at all currently?
  - lazyier 7y ago
    NFS has had caching modes since the beginning. Or at least as long as I have been using it. It's behavior can be controlled by using async or sync options. NFSv4 is actually quite nice. Anything earlier should be avoided.
    - LeoPanthera 7y ago
      Could you elaborate on why it’s nice? I only ask because the OpenBSD maintainer, Theo de Raadt, seems to believe, quite strongly, the opposite: http://openbsd-archive.7691.n7.nabble.com/nfsv4-td18690.html http://openbsd-archive.7691.n7.nabble.com/nfsv4-td18690.html I don’t understand NFS well enough to know what to believe.
      - Hello71 7y ago
        I've seen that thread before but just read it through in its entirety. All I got from it was "OpenBSD people are assholes, and not in the Torvalds 'constructive asshole' way, just in the 'being an asshole for the sake of being an asshole' way".
        skinkestek 7y ago
        Wow, that's impressive in a bad way. Recommended reading for everyone who thought Linus is exceptionally rude and want some nuance.
        AlphaSite 7y ago
        I think Theo is notorious for this.
        samoa42 7y ago
        it is the reason openbsd exists
        tasogare 7y ago
        There is few strong words here and there, but nothing more injurious than what you would hear by staying in a school for 5 minutes. Once you understand the liking of such words by their writers, it's easy to mentally replace them by more politically correct version if it bother you. Moreover, they just critize tech, not people and that's an important distinction imo.
        wtallis 7y ago
        The big problem with that thread isn't profanity or insults or tone. It's that the developers are repeatedly refusing to provide any detail or justification for their less-than-polite assertions that failed to answer the question. Some degree of insults and profanity can be tolerated if there's also useful content, but Henning Brauer and Theo de Raadt didn't make any useful contributions to that thread.
        IntelMiner 7y ago
        Sorry. No. There's no "political correctness" at here Theo's comments in particular seem to start at "NFSv4 is a gigantic joke on everyone." This isn't politically incorrect, it's just noise. Nothing is gained from this comment. Even Linus with his infamous "rants" would have actual commentary laced in, Theo is just being dismissive After someone reaffirms that they would like to use it, he replies "Hahahahaha. That's a good one." "I guess by "all the other protocols" you must be rejecting all the rest of your network traffic as "not protocols" or "not services"." Again. Not helpful, just noise
      - spookthesunset 7y ago
        Wow. What a toxic community. I'd never build a business or platform around a community like that--any time I had a question I'd be constantly worried all the maintainers would bite my head off. Coupled with the fact that I can't be alone in thinking that, I'd also worry about the long term success of a project. And yeah, OpenBSD has been around forever.... but you'd be hard to call them anything more than a tiny little niche operating system. Probably because of how toxic they are.
        mrunkel 7y ago
        It's been that way for a long time: http://openbsd-archive.7691.n7.nabble.com/Oddly-high-load-average-td77479.html http://openbsd-archive.7691.n7.nabble.com/Oddly-high-load-av...
        spookthesunset 7y ago
        Wow. That guy can go fuck himself. In fact every snarky worthless reply to that poor original poster can go fuck themself. Man. That is some hot garbage...
    - reacharavindh 7y ago
      > NFSv4 is nice Wow, never thought I would see this. Are you saying that based on experience or just looking at its feature set? I used to work with NFS performance on NetApp filers at NetApp, and NFSv4(.1,.2) we’re god awful. I used to see almost 1/3 of v3 performance in simple read and write ops. On top of it I need to align all planet to get it to not fail with (EIO) during the test. Is that not the case anymore? Did somebody do some magic I missed in the last couple of years?
      - noselasd 7y ago
        Isn't that more a problem with a specific product (NetApp) ?
  - bonoboTP 7y ago
    Sure, the kernel caches everything in RAM by default (as with any other file system, not just NFS). If you also want to cache on local disk, there's "cachefilesd", which does exactly that. You can specify a certain percentage of the disk that should be kept empty, and cachefilesd will use the rest of the available space for caching. (It works very well, but is broken on kernel 5.x for me (it just doesn't read from the local cache, even though everything looks fine). But I just mention it off-hand, I don't have time to diagnose this in more detail, I just remain on 4.15 for the time being.)
    - lawik 7y ago
      I think this was what I tried to use for one of those shared file system setups for a web app where we needed shared files. And the daemon responsible for this would end up hard-locking the VPS it was running on. Oh yeah, here's the issue I found that mirrored my experience: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=751933 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=751933 That was a rough experience since it would run fine until it hit a certain level of load.
- candiddevmike 7y ago
  You will be able to use this via buster-backports: https://backports.debian.org https://backports.debian.org
- tracker1 7y ago
  I've always had better luck with CIFS/SMB myself... but my exposure is relatively limited.
- beagle3 7y ago
  > It's crazy that the whole system grinds to a near halt if it loses connection to the NFS server, from an end user perspective. Indeed. The only solution that works consistently, if the NFS server is not coming back up anytime soon: Enable an NFS server on localhost; add the address of failed NFS server to a local adapter; wait for retry to finally get an error answer; kill ip address and local NFS server. Client side caching will only delay the inevitable.
nrclark 7y ago
It's great to see all these new features entering the kernel. Here are a couple of other things I've seen in recent changelogs: - The 5.4 kernel can use CIFS as a root filesystem, meaning CIFS can replace NFS for diskless boot. - The 5.3 and 5.4 kernels both include prep for merging PREEMPT_RT into mainline. This will be a fantastic addition that benefits embedded Linux nerds like me.
- lucb1e 7y ago
  For more info on the second point: https://en.wikipedia.org/wiki/Linux_kernel#Preemption https://en.wikipedia.org/wiki/Linux_kernel#Preemption seems to have something to do with real-time operating systems, but I didn't dive into it. Edit: Thanks for the downvotes without commenting what I should do differently next time?
  - zozbot234 7y ago
    Having preemption throughout the whole kernel helps with everything Low-Latency whether on desktop, mobile or server systems; it's not limited to the traditional real-time use case, although it might obviously help there as well to some extent.
  - hactually 7y ago
    It aims to turn Linux into a real-time OS. The preempty patchset aims to give faster response times but the main focus is to remove all unbounded latencies - for example, situations where the delay can vary depending on other factors.
    - jschwartzi 7y ago
      This would kill most use cases for QNX+POSIX.
      - zozbot234 7y ago
        You'll still need QNX if you want to run a full GUI Unix-like OS from a single floppy disk.
Scramblejams 7y ago
Any indication whether this make it into Ubuntu 20.04?
- edoceo 7y ago
  It's gonna be 5.4
- pkaye 7y ago
  They are staying with 5.4 but will back port WireGuard.
  - axaxs 7y ago
    Yikes, that feels like a mistake. 5.4 has awful issues with intel integrated graphics crashing.
    - thayne 7y ago
      The timing is a little unfortunate. 5.6 will be too late to make it in for 20.04, but 5.5 isn't an LTS kernel and 20.04 is an LTS distribution, so I understand not wanting to use 5.5.
      - SlowRobotAhead 7y ago
        The issue of a rigid release schedule! April means April whether you miss out on something or not.
        m-p-3 7y ago
        You still end up having to make compromises no matter what.
        thegeekpirate 7y ago
        One method allows for you to determine which compromises are acceptable, while the other does not.
openthc 7y ago
Wireguard!! Woot! I'll be putting this kernel on all production systems, without testing, on Sunday night while everyone is off.
- terinjokes 7y ago
  What product are you launching tomorrow morning?
  - mehhh 7y ago
    InstaVPN, it mines your traffuc and gives you ICO tokens as a reward!
    - dylz 7y ago
      You're probably joking, but there's several "let us use your connection to ''' mine ''' coin", and as far as I know people are just being used as open proxies for malicious purposes.
  - ioquatix 7y ago
    It's a new blockchain-based analytics database which uses SOAP as the wire protocol.
    - YarickR2 7y ago
      IPO/ICO. Now.
  - openthc 7y ago
    bruv. I was making a dig at another top thread.
    - frandroid 7y ago
      Parent got your point and is joking along
cyphar 7y ago
For some more information on the various features in this release, check out the 5.6-rc1 LWN[1] article. As usual, that article only covers the first week of the merge window (Corbet is probably writing the second part as we speak). [1]: https://lwn.net/SubscriberLink/810780/ae4429af6a4ba40d/ https://lwn.net/SubscriberLink/810780/ae4429af6a4ba40d/
- mrr54 7y ago
  Why are you posting a SubscriberLink to an LWN article to HN? That's not really the point of the links. They're for sharing in small groups not for giving away paid content to thousands of people.
  - andrewaylett 7y ago
    LWN are happy to see them posted: https://news.ycombinator.com/item?id=1966033 https://news.ycombinator.com/item?id=1966033
megous 7y ago
Already compiling... :)
gjsman-1000 7y ago
Rc1 was released just 30 minutes ago! I’m compiling away!
3fe9a03ccd14ca5 7y ago
> Year 2038 work beginning to wrap-up for 32-bit systems I wonder how many of these vulnerable systems will be upgraded to kernel 5.6?
- SlowRobotAhead 7y ago
  ... I’m struggling to think there was ever a reason to store epoch seconds as signed. Was there a use case for “we need to pretend to have 65 years worth of system time before 1970?
  - zzo38computer 7y ago
    Well, now we should use 64-bit timestamps, and 64-bit timestamps is I think sensible to be signed, since there shouldn't need a reason for unsigned 64-bit timestamps.
  - 3fe9a03ccd14ca5 7y ago
    “In 30 years from now everything will probably be 512 bit and flying cars, right?”
    - SlowRobotAhead 7y ago
      That’s the wrong thing. It’s not “will this computer still be running” it’s “does the life of this format work over the time people will use it”. If in 2000 we had 512bit and flying cars, Unix epoch still could be the standard. The first epoch seconds computers aren’t running things anymore. But, it lives on as a standard. So the issue isn’t “was it a good idea to count seconds starting at 1970”, but rather “why the hell would anyone use signed for a value that can only be positive? ... and then keep doing it once they realized the problem!?” 2105 or 2106 wont be an issue for unsigned. No one will use a 32bit standard much longer let alone in the 30 years leading up to the problem date.
  - dredmorbius 7y ago
    From a favourite Reddit thread: - Why in the hell would a date value-- particularly one that's an offset-- be signed? - - How were you planning on indicating dates prior to 1970-01-01? - - - What date before 1970? We just all assume those do not exist. - - - - "Now you've made me feel old." "How old are you?" "Let me put it this way: when I was born, time didn't exist." https://old.reddit.com/r/programming/comments/2b4kpg/conspiracy_and_an_offbyone_error/cj2p2dk/ https://old.reddit.com/r/programming/comments/2b4kpg/conspir... The full context is ... kind of fun: https://old.reddit.com/r/programming/comments/2b4kpg/conspiracy_and_an_offbyone_error/cj1z7x1/?context=3 https://old.reddit.com/r/programming/comments/2b4kpg/conspir...
ddevault 7y ago
Drooling over that picture of a dozen AMD EPYCs. Those processors are seriously awesome. The newest sr.ht server, tenshi.sr.ht, was provisioned to run git.sr.ht and has an EPYC 7402 24-core @ 3.35 GHz at its heart. It can compile the Linux kernel x86_64 defconfig from scratch on an NVMe in under 30 seconds. Our main build server is also EPYC, a 7281.
- SlowRobotAhead 7y ago
  Just bought three Dell 7xxx series with Epyc 7402s. Our IT consultant recommended against AMD in favor of Intel. I didn’t like their reasoning. Side take... I sized our servers to be adequate with the idea virtual cores won’t be turned on. Just assuming more specter and meltdown discoveries, and while AMD has fairer better it’s not impossible they have their own demons.
  - Aperocky 7y ago
    Curious, what are their reasoning?
    - rburhum 7y ago
      you get more for less money and their commission is smaller
    - SlowRobotAhead 7y ago
      I didn’t press but it was along the lines of “everyone uses Intel” and surely would have ended with “no one was ever fired for choosing IBM”. In reality with AMD, the cost was better, the ram/bus was faster, I liked the specs and options of the 7xxx vs the 7xx series better. They couldn’t give me a reason not to chose AMD, only that “Dell always uses Intel for a reason”
      - simonh 7y ago
        >“Dell always uses Intel for a reason” Which is just as likely to be more to do with commercial arm twisting and incentives from Intel than anything technical.
topspin 7y ago
There are a number of new io_uring opcodes appearing with 5.6 as well: fallocate, openat, close, statx, fadvise, madvise, openat2, non-vectored read/write and send/recv.
filereaper 7y ago
Looking forward to multipath TCP. Anyone tried it out yet, how does it look so far?
- londons_explore 7y ago
  Looks good to me, but the Google guys are trying very hard to move the web over to UDP based HTTP/3 instead of MPTCP.
todd3834 7y ago
This sounds like a lot of impressive work. I wonder if there would be any benefit to the Linux kernel adopting more of agile release cycle. This waterfall like release surely has to increase the risk surface. Perhaps the mindset of web software and operating system kernels don’t overlap enough for this to be reasonable?
- todd3834 7y ago
  Not sure why getting downvoted. Is this an ignorant question? Or maybe just not fans of the word agile? Oh well. Guess I’ll just have to ask someone who contributes the the kernel in person the next time I meet one.
  - wtallis 7y ago
    It's a pretty ignorant question; it could also be taken as flamebait trying to start up an agile vs waterfall argument. New stable kernel branches are released every 2-3 months after weekly release candidates, with bugfix releases in between new stable branches and a new LTS branch every year or so. If you want anything "more agile" than that for OS kernel development, then you're probably prioritizing agile dogma over the realities of trying to not break the most fundamental component of the operating system.
    - pmlnr 7y ago
      Agile is juatvas much about small features as time. Imo this kernel comes with too many changes; smaller steps miggt be preferable.
      - wtallis 7y ago
        It sounds like you're just not accustomed to paying attention to a project with such broad scope. Most of these changes have fairly narrow impact on just a single driver or subsystem. It would be silly to say "we're going to postpone release of this new GPU driver because we have too many new network drivers in this release", because there's no reason to expect such a policy to actually improve the quality of kernel releases, and it would obviously be detrimental to the pace of feature additions. Actual far-reaching systemic changes are a pretty small portion of this and most other stable kernel releases.
rmrfchik 7y ago
I've rolled back to 4.19 as 5.x kernels works very bad on my setup. Any IO makes system unresponsive. Box is i7, integrated video, ram 32Gb, SSD 512Gb running debian testing. run "apt update" and mouse stops, music skips. 4.19 runs flawless under any reasonable load on this system.
- jjgreen 7y ago
  I'm seeing the same thing (and have also rolled-back).
  - collyw 7y ago
    My machine won't boot when it tried with a version 5 kernel.
- LinuxBender 7y ago
  What options do you see in /proc/cmdline when you are on 5.x?
  - LinuxBender 7y ago
    And could you add the output of 'lspci -vv' perhaps on pastebin
pjmlp 7y ago
> Intel MPX support is completely removed. A bit sad about this one, Intel should talk to Oracle, ARM and Cambridge Computer Laboratory on how to implement this kind of feature properly.
jeena 7y ago
It's interesting to see how adding of features correlates with the quality of a software. I haven't had problems with wifi on Linux since 2012 (when I came back to it from OS X after leaving 2006 with huge problems before NetworkManager was introduced, etc.). It was until two or three months ago after a kernel update my laptop started dropping the connection with my 5 Ghz network, only at home. It seems to be a common problem with the Qualcom chip driver which worked nice on this laptop for almost two years. I like progressiveness a lot and also new features, etc. and I found a workaround (switched off 5Ghz at home), so it's ok and I can always install an older kernel too which is the freedom of free software, I wasn't able to do stuff like that on OS X.
- theelous3 7y ago
  Ah! I should try this! Arch on a dell xps, fine for two years and now have some issue where network buffer doesn't flush (cursory investigation). Have been fairly sure it's an issue post update. Thanks for the idea :)
  - jeena 7y ago
    Yeah mine is a XPS 13 with Arch on it.
- zozbot234 7y ago
  Quality regressions are common when running bleeding-edge software, this is why going with something LTS is recommended for actual productive use. Now if average non-enterprise folks could get a proper, LTS version of Windows 10...
- tsar9x 7y ago
  Intel iGPU driver (i915) is broken in 5.4 release, I think there are still big issues with QA.
stefs 7y ago
i don't really understand this: "The AMD k10temp driver finally starts reporting voltage/current for Zen CPUs and numerous thermal reporting improvements. This is a big step forward thanks to the community but unfortunate these Zen/Zen2 thermal/power reporting bits have taken so long and there are still some mysteries that remain." why wouldn't AMD set aside a couple of engineers (or at least one) to make sure their processors are supported here? it's not like this would be a huge drain on their manpower resources and the company itself should have an immense interest in the best possible linux support.
- thescriptkiddie 7y ago
  Zen CPUs are notoriously broken on Linux and AMD doesn't seem to care. If you ever try to install Linux on a first-get Ryzen box and want an uptime longer than 3 days, you'll want to keep this handy: https://github.com/qrwteyrutiyoup/ryzen-stabilizator https://github.com/qrwteyrutiyoup/ryzen-stabilizator
  - sq_ 7y ago
    I’m not sure if I’m some weird exception, but I’ve never had issues running Linux at long uptimes on my R5 1600 box.
    - ohithereyou 7y ago
      It wouldn't surprise me if the quality and stability of the motherboard is a factor here. R5 1600, never had any of these problems, and I have friends running Threadrippers that don't see these problems either.
      - sq_ 7y ago
        Seems plausible. The build my R5 1600 is in has a reasonably high-end Asrock X370 mobo. Is your setup similar?
        ohithereyou 7y ago
purplezooey 7y ago
crap there's a USB4 already?
Andrex 7y ago
The Year 2038 stuff is cool. Do we have projections for how much unpatched stuff might still be around in 2038 to cause issues? The benefit of getting the fixes merged 18 years ahead of time is so those fixes proliferate, but I have to imagine there's a nonzero amount that won't/can't upgrade... Curious if there's any idea of how big an issue this could be, even if we solved everything today.
JohnFen 7y ago
There's certainly a lot in there! However, there's not much that is of interest to me. Given that, plus the mammoth amount of changes in the kernel, I think that I'll be delaying updating to this kernel for a good, long time. Just in case.

714 points by alexellisuk 7y ago

I'm really excited about the NFS client cache stuff. It's crazy that the whole system grinds to a near halt if it loses connection to the NFS server, from an end user perspective. I look forward to some time in the future when Debian incorporates this kernel. I prefer to use stock kernels. I used to enjoy messing with my distros, but these days I prefer stability.

LeoPanthera 7y ago
I’m not an NFS expert, and I’ve often wondered about client caching of NFS to improve performance. Does this exist at all currently?
- lazyier 7y ago
  NFS has had caching modes since the beginning. Or at least as long as I have been using it. It's behavior can be controlled by using async or sync options. NFSv4 is actually quite nice. Anything earlier should be avoided.
  - LeoPanthera 7y ago
    Could you elaborate on why it’s nice? I only ask because the OpenBSD maintainer, Theo de Raadt, seems to believe, quite strongly, the opposite: http://openbsd-archive.7691.n7.nabble.com/nfsv4-td18690.html http://openbsd-archive.7691.n7.nabble.com/nfsv4-td18690.html I don’t understand NFS well enough to know what to believe.
    - Hello71 7y ago
      I've seen that thread before but just read it through in its entirety. All I got from it was "OpenBSD people are assholes, and not in the Torvalds 'constructive asshole' way, just in the 'being an asshole for the sake of being an asshole' way".
      - skinkestek 7y ago
        Wow, that's impressive in a bad way. Recommended reading for everyone who thought Linus is exceptionally rude and want some nuance.
        AlphaSite 7y ago
        I think Theo is notorious for this.
        samoa42 7y ago
        it is the reason openbsd exists
      - tasogare 7y ago
        There is few strong words here and there, but nothing more injurious than what you would hear by staying in a school for 5 minutes. Once you understand the liking of such words by their writers, it's easy to mentally replace them by more politically correct version if it bother you. Moreover, they just critize tech, not people and that's an important distinction imo.
        wtallis 7y ago
        The big problem with that thread isn't profanity or insults or tone. It's that the developers are repeatedly refusing to provide any detail or justification for their less-than-polite assertions that failed to answer the question. Some degree of insults and profanity can be tolerated if there's also useful content, but Henning Brauer and Theo de Raadt didn't make any useful contributions to that thread.
        IntelMiner 7y ago
        Sorry. No. There's no "political correctness" at here Theo's comments in particular seem to start at "NFSv4 is a gigantic joke on everyone." This isn't politically incorrect, it's just noise. Nothing is gained from this comment. Even Linus with his infamous "rants" would have actual commentary laced in, Theo is just being dismissive After someone reaffirms that they would like to use it, he replies "Hahahahaha. That's a good one." "I guess by "all the other protocols" you must be rejecting all the rest of your network traffic as "not protocols" or "not services"." Again. Not helpful, just noise
    - spookthesunset 7y ago
      Wow. What a toxic community. I'd never build a business or platform around a community like that--any time I had a question I'd be constantly worried all the maintainers would bite my head off. Coupled with the fact that I can't be alone in thinking that, I'd also worry about the long term success of a project. And yeah, OpenBSD has been around forever.... but you'd be hard to call them anything more than a tiny little niche operating system. Probably because of how toxic they are.
      - mrunkel 7y ago
        It's been that way for a long time: http://openbsd-archive.7691.n7.nabble.com/Oddly-high-load-average-td77479.html http://openbsd-archive.7691.n7.nabble.com/Oddly-high-load-av...
        spookthesunset 7y ago
        Wow. That guy can go fuck himself. In fact every snarky worthless reply to that poor original poster can go fuck themself. Man. That is some hot garbage...
  - reacharavindh 7y ago
    > NFSv4 is nice Wow, never thought I would see this. Are you saying that based on experience or just looking at its feature set? I used to work with NFS performance on NetApp filers at NetApp, and NFSv4(.1,.2) we’re god awful. I used to see almost 1/3 of v3 performance in simple read and write ops. On top of it I need to align all planet to get it to not fail with (EIO) during the test. Is that not the case anymore? Did somebody do some magic I missed in the last couple of years?
    - noselasd 7y ago
      Isn't that more a problem with a specific product (NetApp) ?
- bonoboTP 7y ago
  Sure, the kernel caches everything in RAM by default (as with any other file system, not just NFS). If you also want to cache on local disk, there's "cachefilesd", which does exactly that. You can specify a certain percentage of the disk that should be kept empty, and cachefilesd will use the rest of the available space for caching. (It works very well, but is broken on kernel 5.x for me (it just doesn't read from the local cache, even though everything looks fine). But I just mention it off-hand, I don't have time to diagnose this in more detail, I just remain on 4.15 for the time being.)
  - lawik 7y ago
    I think this was what I tried to use for one of those shared file system setups for a web app where we needed shared files. And the daemon responsible for this would end up hard-locking the VPS it was running on. Oh yeah, here's the issue I found that mirrored my experience: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=751933 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=751933 That was a rough experience since it would run fine until it hit a certain level of load.
candiddevmike 7y ago
You will be able to use this via buster-backports: https://backports.debian.org https://backports.debian.org
tracker1 7y ago
I've always had better luck with CIFS/SMB myself... but my exposure is relatively limited.
beagle3 7y ago
> It's crazy that the whole system grinds to a near halt if it loses connection to the NFS server, from an end user perspective. Indeed. The only solution that works consistently, if the NFS server is not coming back up anytime soon: Enable an NFS server on localhost; add the address of failed NFS server to a local adapter; wait for retry to finally get an error answer; kill ip address and local NFS server. Client side caching will only delay the inevitable.

nrclark 7y ago

It's great to see all these new features entering the kernel. Here are a couple of other things I've seen in recent changelogs: - The 5.4 kernel can use CIFS as a root filesystem, meaning CIFS can replace NFS for diskless boot. - The 5.3 and 5.4 kernels both include prep for merging PREEMPT_RT into mainline. This will be a fantastic addition that benefits embedded Linux nerds like me.

lucb1e 7y ago
For more info on the second point: https://en.wikipedia.org/wiki/Linux_kernel#Preemption https://en.wikipedia.org/wiki/Linux_kernel#Preemption seems to have something to do with real-time operating systems, but I didn't dive into it. Edit: Thanks for the downvotes without commenting what I should do differently next time?
- zozbot234 7y ago
  Having preemption throughout the whole kernel helps with everything Low-Latency whether on desktop, mobile or server systems; it's not limited to the traditional real-time use case, although it might obviously help there as well to some extent.
- hactually 7y ago
  It aims to turn Linux into a real-time OS. The preempty patchset aims to give faster response times but the main focus is to remove all unbounded latencies - for example, situations where the delay can vary depending on other factors.
  - jschwartzi 7y ago
    This would kill most use cases for QNX+POSIX.
    - zozbot234 7y ago
      You'll still need QNX if you want to run a full GUI Unix-like OS from a single floppy disk.

Scramblejams 7y ago

Any indication whether this make it into Ubuntu 20.04?

edoceo 7y ago
It's gonna be 5.4
pkaye 7y ago
They are staying with 5.4 but will back port WireGuard.
- axaxs 7y ago
  Yikes, that feels like a mistake. 5.4 has awful issues with intel integrated graphics crashing.
  - thayne 7y ago
    The timing is a little unfortunate. 5.6 will be too late to make it in for 20.04, but 5.5 isn't an LTS kernel and 20.04 is an LTS distribution, so I understand not wanting to use 5.5.
    - SlowRobotAhead 7y ago
      The issue of a rigid release schedule! April means April whether you miss out on something or not.
      - m-p-3 7y ago
        You still end up having to make compromises no matter what.
        thegeekpirate 7y ago
        One method allows for you to determine which compromises are acceptable, while the other does not.

openthc 7y ago

Wireguard!! Woot! I'll be putting this kernel on all production systems, without testing, on Sunday night while everyone is off.

terinjokes 7y ago
What product are you launching tomorrow morning?
- mehhh 7y ago
  InstaVPN, it mines your traffuc and gives you ICO tokens as a reward!
  - dylz 7y ago
    You're probably joking, but there's several "let us use your connection to ''' mine ''' coin", and as far as I know people are just being used as open proxies for malicious purposes.
- ioquatix 7y ago
  It's a new blockchain-based analytics database which uses SOAP as the wire protocol.
  - YarickR2 7y ago
    IPO/ICO. Now.
- openthc 7y ago
  bruv. I was making a dig at another top thread.
  - frandroid 7y ago
    Parent got your point and is joking along

cyphar 7y ago

For some more information on the various features in this release, check out the 5.6-rc1 LWN[1] article. As usual, that article only covers the first week of the merge window (Corbet is probably writing the second part as we speak). [1]: https://lwn.net/SubscriberLink/810780/ae4429af6a4ba40d/ https://lwn.net/SubscriberLink/810780/ae4429af6a4ba40d/

mrr54 7y ago
Why are you posting a SubscriberLink to an LWN article to HN? That's not really the point of the links. They're for sharing in small groups not for giving away paid content to thousands of people.
- andrewaylett 7y ago
  LWN are happy to see them posted: https://news.ycombinator.com/item?id=1966033 https://news.ycombinator.com/item?id=1966033

megous 7y ago

Already compiling... :)

gjsman-1000 7y ago

Rc1 was released just 30 minutes ago! I’m compiling away!

3fe9a03ccd14ca5 7y ago

> Year 2038 work beginning to wrap-up for 32-bit systems I wonder how many of these vulnerable systems will be upgraded to kernel 5.6?

SlowRobotAhead 7y ago
... I’m struggling to think there was ever a reason to store epoch seconds as signed. Was there a use case for “we need to pretend to have 65 years worth of system time before 1970?
- zzo38computer 7y ago
  Well, now we should use 64-bit timestamps, and 64-bit timestamps is I think sensible to be signed, since there shouldn't need a reason for unsigned 64-bit timestamps.
- 3fe9a03ccd14ca5 7y ago
  “In 30 years from now everything will probably be 512 bit and flying cars, right?”
  - SlowRobotAhead 7y ago
    That’s the wrong thing. It’s not “will this computer still be running” it’s “does the life of this format work over the time people will use it”. If in 2000 we had 512bit and flying cars, Unix epoch still could be the standard. The first epoch seconds computers aren’t running things anymore. But, it lives on as a standard. So the issue isn’t “was it a good idea to count seconds starting at 1970”, but rather “why the hell would anyone use signed for a value that can only be positive? ... and then keep doing it once they realized the problem!?” 2105 or 2106 wont be an issue for unsigned. No one will use a 32bit standard much longer let alone in the 30 years leading up to the problem date.
- dredmorbius 7y ago
  From a favourite Reddit thread: - Why in the hell would a date value-- particularly one that's an offset-- be signed? - - How were you planning on indicating dates prior to 1970-01-01? - - - What date before 1970? We just all assume those do not exist. - - - - "Now you've made me feel old." "How old are you?" "Let me put it this way: when I was born, time didn't exist." https://old.reddit.com/r/programming/comments/2b4kpg/conspiracy_and_an_offbyone_error/cj2p2dk/ https://old.reddit.com/r/programming/comments/2b4kpg/conspir... The full context is ... kind of fun: https://old.reddit.com/r/programming/comments/2b4kpg/conspiracy_and_an_offbyone_error/cj1z7x1/?context=3 https://old.reddit.com/r/programming/comments/2b4kpg/conspir...

ddevault 7y ago

Drooling over that picture of a dozen AMD EPYCs. Those processors are seriously awesome. The newest sr.ht server, tenshi.sr.ht, was provisioned to run git.sr.ht and has an EPYC 7402 24-core @ 3.35 GHz at its heart. It can compile the Linux kernel x86_64 defconfig from scratch on an NVMe in under 30 seconds. Our main build server is also EPYC, a 7281.

SlowRobotAhead 7y ago
Just bought three Dell 7xxx series with Epyc 7402s. Our IT consultant recommended against AMD in favor of Intel. I didn’t like their reasoning. Side take... I sized our servers to be adequate with the idea virtual cores won’t be turned on. Just assuming more specter and meltdown discoveries, and while AMD has fairer better it’s not impossible they have their own demons.
- Aperocky 7y ago
  Curious, what are their reasoning?
  - rburhum 7y ago
    you get more for less money and their commission is smaller
  - SlowRobotAhead 7y ago
    I didn’t press but it was along the lines of “everyone uses Intel” and surely would have ended with “no one was ever fired for choosing IBM”. In reality with AMD, the cost was better, the ram/bus was faster, I liked the specs and options of the 7xxx vs the 7xx series better. They couldn’t give me a reason not to chose AMD, only that “Dell always uses Intel for a reason”
    - simonh 7y ago
      >“Dell always uses Intel for a reason” Which is just as likely to be more to do with commercial arm twisting and incentives from Intel than anything technical.

topspin 7y ago

There are a number of new io_uring opcodes appearing with 5.6 as well: fallocate, openat, close, statx, fadvise, madvise, openat2, non-vectored read/write and send/recv.

filereaper 7y ago

Looking forward to multipath TCP. Anyone tried it out yet, how does it look so far?

londons_explore 7y ago
Looks good to me, but the Google guys are trying very hard to move the web over to UDP based HTTP/3 instead of MPTCP.

todd3834 7y ago

This sounds like a lot of impressive work. I wonder if there would be any benefit to the Linux kernel adopting more of agile release cycle. This waterfall like release surely has to increase the risk surface. Perhaps the mindset of web software and operating system kernels don’t overlap enough for this to be reasonable?

todd3834 7y ago
Not sure why getting downvoted. Is this an ignorant question? Or maybe just not fans of the word agile? Oh well. Guess I’ll just have to ask someone who contributes the the kernel in person the next time I meet one.
- wtallis 7y ago
  It's a pretty ignorant question; it could also be taken as flamebait trying to start up an agile vs waterfall argument. New stable kernel branches are released every 2-3 months after weekly release candidates, with bugfix releases in between new stable branches and a new LTS branch every year or so. If you want anything "more agile" than that for OS kernel development, then you're probably prioritizing agile dogma over the realities of trying to not break the most fundamental component of the operating system.
  - pmlnr 7y ago
    Agile is juatvas much about small features as time. Imo this kernel comes with too many changes; smaller steps miggt be preferable.
    - wtallis 7y ago
      It sounds like you're just not accustomed to paying attention to a project with such broad scope. Most of these changes have fairly narrow impact on just a single driver or subsystem. It would be silly to say "we're going to postpone release of this new GPU driver because we have too many new network drivers in this release", because there's no reason to expect such a policy to actually improve the quality of kernel releases, and it would obviously be detrimental to the pace of feature additions. Actual far-reaching systemic changes are a pretty small portion of this and most other stable kernel releases.

rmrfchik 7y ago

I've rolled back to 4.19 as 5.x kernels works very bad on my setup. Any IO makes system unresponsive. Box is i7, integrated video, ram 32Gb, SSD 512Gb running debian testing. run "apt update" and mouse stops, music skips. 4.19 runs flawless under any reasonable load on this system.

jjgreen 7y ago
I'm seeing the same thing (and have also rolled-back).
- collyw 7y ago
  My machine won't boot when it tried with a version 5 kernel.
LinuxBender 7y ago
What options do you see in /proc/cmdline when you are on 5.x?
- LinuxBender 7y ago
  And could you add the output of 'lspci -vv' perhaps on pastebin

pjmlp 7y ago

> Intel MPX support is completely removed. A bit sad about this one, Intel should talk to Oracle, ARM and Cambridge Computer Laboratory on how to implement this kind of feature properly.

jeena 7y ago

It's interesting to see how adding of features correlates with the quality of a software. I haven't had problems with wifi on Linux since 2012 (when I came back to it from OS X after leaving 2006 with huge problems before NetworkManager was introduced, etc.). It was until two or three months ago after a kernel update my laptop started dropping the connection with my 5 Ghz network, only at home. It seems to be a common problem with the Qualcom chip driver which worked nice on this laptop for almost two years. I like progressiveness a lot and also new features, etc. and I found a workaround (switched off 5Ghz at home), so it's ok and I can always install an older kernel too which is the freedom of free software, I wasn't able to do stuff like that on OS X.

theelous3 7y ago
Ah! I should try this! Arch on a dell xps, fine for two years and now have some issue where network buffer doesn't flush (cursory investigation). Have been fairly sure it's an issue post update. Thanks for the idea :)
- jeena 7y ago
  Yeah mine is a XPS 13 with Arch on it.
zozbot234 7y ago
Quality regressions are common when running bleeding-edge software, this is why going with something LTS is recommended for actual productive use. Now if average non-enterprise folks could get a proper, LTS version of Windows 10...
tsar9x 7y ago
Intel iGPU driver (i915) is broken in 5.4 release, I think there are still big issues with QA.

stefs 7y ago

i don't really understand this: "The AMD k10temp driver finally starts reporting voltage/current for Zen CPUs and numerous thermal reporting improvements. This is a big step forward thanks to the community but unfortunate these Zen/Zen2 thermal/power reporting bits have taken so long and there are still some mysteries that remain." why wouldn't AMD set aside a couple of engineers (or at least one) to make sure their processors are supported here? it's not like this would be a huge drain on their manpower resources and the company itself should have an immense interest in the best possible linux support.

thescriptkiddie 7y ago
Zen CPUs are notoriously broken on Linux and AMD doesn't seem to care. If you ever try to install Linux on a first-get Ryzen box and want an uptime longer than 3 days, you'll want to keep this handy: https://github.com/qrwteyrutiyoup/ryzen-stabilizator https://github.com/qrwteyrutiyoup/ryzen-stabilizator
- sq_ 7y ago
  I’m not sure if I’m some weird exception, but I’ve never had issues running Linux at long uptimes on my R5 1600 box.
  - ohithereyou 7y ago
    It wouldn't surprise me if the quality and stability of the motherboard is a factor here. R5 1600, never had any of these problems, and I have friends running Threadrippers that don't see these problems either.
    - sq_ 7y ago
      Seems plausible. The build my R5 1600 is in has a reasonably high-end Asrock X370 mobo. Is your setup similar?
      - ohithereyou 7y ago

purplezooey 7y ago

crap there's a USB4 already?

Andrex 7y ago

The Year 2038 stuff is cool. Do we have projections for how much unpatched stuff might still be around in 2038 to cause issues? The benefit of getting the fixes merged 18 years ahead of time is so those fixes proliferate, but I have to imagine there's a nonzero amount that won't/can't upgrade... Curious if there's any idea of how big an issue this could be, even if we solved everything today.

JohnFen 7y ago

There's certainly a lot in there! However, there's not much that is of interest to me. Given that, plus the mammoth amount of changes in the kernel, I think that I'll be delaying updating to this kernel for a good, long time. Just in case.