DblPlusUngood

6 ms·

1.
by DblPlusUngood 5y ago
Yes.
2.
by DblPlusUngood 5y ago
In some cases, yes (if there are other runnable threads on this CPU's queue).
3.
by DblPlusUngood 5y ago
A better example: a page fault for a non-present page.
4.
by DblPlusUngood 7y ago
Don't forget gltron!
5.
by DblPlusUngood 7y ago
You are absolutely right. They are used everywhere in the Linux, OpenBSD, and FreeBSD kernels, and likely many other kernels. Replacing large linked lists with arrays is rarely an actual win. With an array, insertion and deletion become far
6.
by DblPlusUngood 7y ago
> I don't see how it could. Kernel data structures don't go on pagecache pages. Kernel data structures could end up on a pagecache page: all it takes is a reference counting bug and the page could be reallocated in the kernel h
7.
by DblPlusUngood 7y ago
OpenBSD's choice is arguably reasonable, given their prioritization of security, since it reduces opportunities for user programs to corrupt kernel memory. What is the problem with OpenBSD's plan for coherency? Why is the burden o
8.
by DblPlusUngood 7y ago
What coherence is lacking? OpenBSD supports msync(2), which is the only POSIX mechanism I know of for ensuring coherency between read(2) and shared file mappings. Otherwise relying on unspecified behavior sounds dangerous.
9.
by DblPlusUngood 7y ago
OpenSSH does have confirmation: use the '-c' switch to ssh-add. https://man.openbsd.org/ssh-add
10.
by DblPlusUngood 7y ago
Is recovery of a shared memory queue after one of the workers crashes even possible, in general? (what if the worker crashed before releasing a lock?)
11.
by DblPlusUngood 8y ago
Sounds like a fun project! Isn't seL4's multicore support either unverified or limited (i.e. shared memory is forbidden)? Is your platform single-threaded then?
12.
by DblPlusUngood 8y ago
Yes. In theory, maybe it's useful to have more flexibility to trade-off durability for performance (smaller quorum size hopefully reduces deciding latency [unless your small quorum contains the straggler!]) for specific kinds of data i
13.
by DblPlusUngood 8y ago
Instead of an ad hominem, please clearly explain the main way that the example Go code is less safe than the C example code.
14.
by DblPlusUngood 8y ago
This is a great point. Jargon can be really intimidating and make the simplest statements impossible to understand for the unfamiliar. But is often trivial to learn with a little study.
15.
by DblPlusUngood 8y ago
A particularly tricky task with GNU make is automatically adding target dependencies on header files and handling updates to them (gcc's -M and -MMD switches). It would be great if the article explained those best practices, too.
16.
by DblPlusUngood 8y ago
How are GCs not compatible with bounded memory use? Though many GCs size allocation arenas proportionally to the live data, there is no fundamental reason why the allocation arenas couldn't be fixed-size (of course, they must be large
17.
by DblPlusUngood 8y ago
Well, for one thing, zig apparently has no built-in memory allocator?
18.
by DblPlusUngood 8y ago
Turns out the x86 already has some bounds checking support; see chapter 17 in volume 1 of Intel's developer manuals and the BOUND and BND* instructions.
19.
by DblPlusUngood 8y ago
> I love the BSDs and especially OpenBSD for their attention to manpages. It's the main reason why I don't use Linux anymore unless I have to. I completely agree. The difference in the quality of manpages between OpenBSD and
20.
by DblPlusUngood 8y ago
1. I wouldn't say we are skeptical of Rust, I'm sure it could be made to work well and we would love to see such a Rust kernel! I do wonder whether it would be harder to implement highly-concurrent data structures in Rust though,
21.
by DblPlusUngood 8y ago
Hah, I am Cody and I'm not related to Dave Cutler (as far as I know!).
22.
by DblPlusUngood 8y ago
Concerning your first question, that experiment is not intended to measure the cost of GC, which can be made small by trading memory. The point of this experiment is to measure the unavoidable costs of the language.
23.
by DblPlusUngood 8y ago
Well that was fast! I'm an author of this paper and would be happy to answer questions.
24.
by DblPlusUngood 8y ago
Different Linux kernel config options, probably. Different options can drastically affect performance.
25.
by DblPlusUngood 8y ago
That's correct. The primary performance benefit of generational GC (in terms of throughput and maybe also latency) is that it can reclaim the memory (backing the young generation) without marking or otherwise processing the vast majori
26.
by DblPlusUngood 10y ago
No, the size of the array doesn't need to be a power-of-2 if you use modulus to derive indices. But you need to deal with the overflow somehow. For instance: 0xffffffff % 7 = 3, but (0xffffffff + 1) % 7 = 0.
27.
by DblPlusUngood 10y ago
I guess the browser calls system(3) on the arbitrary URI instead of directly exec'ing /usr/bin/nnrurlshow? How amusing.
28.
by DblPlusUngood 10y ago
You are addressing criticisms of Stalin with a logical fallacy called "whataboutism".
29.
by DblPlusUngood 10y ago
I don't understand you. Is your answer to my question: "Modern UNIX OSes cannot take advantage of said ideas because they are POSIX compatible."?
30.
by DblPlusUngood 10y ago
> "...while lots of different, great ideas about computing and networks have been developed in the last 30 years." > What we really need are OSes that take the ideas from human-computer interaction from Xerox PARC and Viewpo

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