11–20 of 82 posts
https://github.com/compudj/librseq
This has helpers for common use cases like counters and linked lists. You shouldn't need to write assembly at all to use rseq in most applications.
Restartable windows, or more generically introspection windows, are a really useful technique you can apply in any situation where you understand or control the sources of preemption. The earliest uses of this technique in operating systems that I am aware of are ~25 years old. The key insight is that the preempter can introspect the program counter of the code being preempted (which is now stable since it was preemp…
If you had no idea what a restorable sequence is the takeaway is about halfway down the OP: “This is why Linux now provides rseq() which is a much more enlightened solution. With restartable sequences, you actually can get rid of both the mutex and atomics, while the OS continues to fully abstract scheduling. The way it works is you advise the kernel whenever your program enters a critical section of code that you do…
(Based on my reading of the LWN article rwmj posted).
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If you had no idea what a restorable sequence is the takeaway is about halfway down the OP: “This is why Linux now provides rseq() which is a much more enlightened solution. With restartable sequences, you actually can get rid of both the mutex and atomics, while the OS continues to fully abstract scheduling. The way it works is you advise the kernel whenever your program enters a critical section of code that you do…
That doesn't really explain it though, IMO. IIUC, it's a sequence of instructions that either runs to completion atomically or doesn't. If it is interrupted by anything the kernel jumps you to the abort/retry vector you set with a guarantee that the last instruction in the sequence was not executed. (Based on my reading of the LWN article rwmj posted).
There is a time-slice extension feature in the works that's roughly "please let me finish this critical section before you interrupt me". But a hard guarantee that userspace code won't be interrupted is probably untenable in a preemptive multitasking system.
Maybe I'm just getting old but the "if you don't spend $20,000 on a workstation you're going to be left behind like a dinosaur" at the top of this article is a huge turn off to reading any further. And I say that as someone who owns a workstation with more cores than the author's.
Maybe I'm just getting old but the "if you don't spend $20,000 on a workstation you're going to be left behind like a dinosaur" at the top of this article is a huge turn off to reading any further. And I say that as someone who owns a workstation with more cores than the author's.
The author was also asking for money to buy a house in SF and travel on private planes like a few days ago..the donation must have really showed up if they are using 20k machines at home.
Maybe I'm just getting old but the "if you don't spend $20,000 on a workstation you're going to be left behind like a dinosaur" at the top of this article is a huge turn off to reading any further. And I say that as someone who owns a workstation with more cores than the author's.