mtanski

8 ms·

31.
by mtanski 9y ago
I'm thinking you might be right. It's going to be really hard to give up real world gains from branch prediction. Branch prediction can make a lot of real world (read "not the finest code in the world") run at reasonable
32.
by mtanski 9y ago
After thinking about this I think you may be right. It might be hard (or impossible to do in practice). > or within the same space as the executing address That's probably a good place to start from. I'm guessing there still wo
33.
by mtanski 9y ago
Speculative execution as a concept should not be flawed. My take is that the results of illegal speculation should never be leaked in a visable way.
34.
by mtanski 9y ago
JIT engines (and compilers) often generate a familiar instruction patterns. Many JIT engines Target specific languages (like JS) and as result have "simpler" optimizers (less time to do this) and possibly more stable instruction p
35.
by mtanski 9y ago
Please re-read my above comment. There is no new API. The DAX userspace API is mmap. This work is experimental but you can mmap a single file on a filesystem on this device using new DAX capabilities. Most access will not longer require a s
36.
by mtanski 9y ago
The claim is that it's 2% to 5% in most general uses on systems that have PCID support. If that's the case then I'm willing to bet that databases on fast flash storage are lot more impacted then this and pure CPU bound tasks
37.
by mtanski 9y ago
If you bypass the page cache you do not have read()/write() and mmap you avoid the syscall overhead. This matters a lot for high IOPs devices. Also these new fangled devices claim support word cache line sync using normal cpu flush ins
38.
by mtanski 9y ago
We're still learning, but it looks like pgbench is 7% to 15% off: https://www.postgresql.org/message-id/20180102222354.qikjmf7...
39.
by mtanski 9y ago
I think the model for cloud vendors would be quite complicated. Not every version of the CPU and not every application is impacted as much (new intel processors with PCID will suffer less). Add on top of that the fact that a lot cloud custo
40.
by mtanski 9y ago
This comment further down thread mentions it's 20% in Postgres. https://news.ycombinator.com/item?id=16061926
41.
by mtanski 9y ago
In the future this possible on Linux with the filesystems that support DAX. Currently this all pretty experimental with lots of work being done in this space in the last two years. But this will require you to have the right kind of flash s
42.
by mtanski 9y ago
As I mentioned in the other thread yesterday database and database like applications are going to be hit particular hard. Even more so on fast flash storage. Double whammy compared to apps just doing network IO. And while databases try to m
43.
by mtanski 9y ago
It sounds like databases on very fast storage will be updated. Tons of syscalls made for disk io and network io.
44.
by mtanski 9y ago
How's that? Weworks is buying in one market and reselling (with value adds) in a different market and profiting off this difference. They lease large commercial (multi-story) offices from owners and building management companies and re
45.
by mtanski 9y ago
Price controls is a dirty term we refuse to talk about in the good 'ol USA. Most other healthcare systems in the world with low prices have some kind of combination of it when it comes to drugs and procedures performed. The AMA has bee
46.
by mtanski 9y ago
Their business model is not complicated. They arbitrage office space. Office space is expensive to rent (operationally), takes a long time to find a tenant, and there's a lot of different kinds of leases (short/long term) and most
47.
by mtanski 9y ago
firmware needed by modern nvidia cards is cryptographically signed
48.
by mtanski 9y ago
In an ideal world poor quality publications regardless of audience size would end up being penalized for poor quality reporting. Sadly, the world is not ideal and markets at best an approximation of efficient markets. CNBC is prime example
49.
by mtanski 9y ago
Talk about a shitty god.
50.
by mtanski 9y ago
As somebody who’s debugged and inspected machine code generated by expanded templates I can tell you this is not really a problem. At -O2 or -O3 optimization level with GCC or Clang almost all of that get unlined, removed, remerged and just
51.
by mtanski 9y ago
If you have day old bread it's "legacy crust". And, who wants legacy crust.
52.
by mtanski 9y ago
This was my original model when I came up with the idea; in fact, my v1 hack used recv and MSG_DONTWAIT. For a number of a reasons the kernel community did not want to overload that interface and that flag. Besides some technical reasons, t
53.
by mtanski 9y ago
In really new linux there is a preadv2 sysscall that was merged. preadv2 supports a flag RWF_NOWAIT to tell the kernel to not block if a read requires uncached data. This lets you play around with policy for blocking reads in user space. Ex
54.
by mtanski 9y ago
LWN has had quite a few past articles that went into details of issues with processing network packets at line speeds on modern OSes and machines. https://lwn.net/Articles/629155/ https://lwn.net/A
55.
by mtanski 9y ago
Not to mention, there's a non-insignificant portion of the population that's allergic. Generally it's not life threatening but most commonly it'll lead to cold like symptoms (nose/head congestion, trouble sleeping).
56.
by mtanski 9y ago
In principle that's true... In reality 1. You can be shot by a cop even if you do not pose a real threat (they just need to claim they though you might have a gun, simple) 2. People are routinely kept in jail for unreasonably long time
57.
by mtanski 9y ago
> I think one of the best outcomes of a competitive CPU market is that the artificial limitations Intel introduced to segment their CPU market are going to have to die. Actually, for me following at home ... it seams like they have a who
58.
by mtanski 9y ago
I understand the mission of the ACLU, including their representation of people I agree with / don't agree with. But, I'm not quite sure why they are representing Milo... mostly because he can afford and their resources are be
59.
by mtanski 9y ago
If this was a trial then and I believed he was unjustly fired I'd be right there with you. But we're now in the court of public opinion and I'm not really sure it's in his best interest to speak up.
60.
by mtanski 9y ago
> When the whole episode finally became a giant media controversy This is a bit self referential. But seriously who cares. People get fired daily, many of them get fired unjustly... and you know what we don't write tons and tons of

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