Messages in this thread |  | | Subject | Re: low-latency patches | From | Robert Love <> | Date | 06 Oct 2001 18:36:49 -0400 |
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On Sat, 2001-10-06 at 02:05, Bob McElrath wrote: > [...] > Correct me if I'm wrong, but the former uses spinlocks to know when it can > preempt the kernel, and the latter just tries to reduce latency by adding > (un)conditional_schedule and placing it at key places in the kernel?
Correct. The low-latency patch does some other work to try to break up huge routines, too.
> My questions are: > 1) Which of these two projects has better latency performance? Has anyone > benchmarked them against each other?
I suspect you will find a lower average latency with the preemption patch. However, I suspect with the low-latency patch you may see a lower maximum since it works on some of the terribly long-held lock situations.
In truth, a combination of the two could prove useful. I have been working on finding the worst-case non-preemption regions (longest held lock regions) in the kernel.
> 2) Will either of these ever be merged into Linus' kernel (2.5?)
I hope :)
> 3) Is there a possibility that either of these will make it to non-x86 > platforms? (for me: alpha) The second patch looks like it would > straightforwardly work on any arch, but the config.in for it is only in > arch/i386. Robert Love's patches would need some arch-specific asm...
Andrew's patch should work fine on all platforms, although I think the configure statement is in the processor section so you will need to move it to arch/alpha/config.in
The preemption patch has a small amount of arch-independent code but we are working on supporting all architectures. 2.5...
Robert Love
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