[Fwd: low-latency patches]
PATCH 1/1 [Fwd: low-latency patches]
Quoted 9 lines · Bob McElrath
It seems there are two low-latency projects out there. The one by Robert Love:
http://tech9.net/rml/linux/and the original one:
http://www.uow.edu.au/~andrewm/linux/schedlat.htmlCorrect 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?
Quoted 8 lines
My questions are:
1) Which of these two projects has better latency performance? Has anyone benchmarked them against each other?
2) Will either of these ever be merged into Linus' kernel (2.5?)
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 inarch/i386. Robert Love's patches would need some arch-specific asm...
In my experience with them, the Andrew Morton patches provide a "smoother" interactive feel, great for things like online gaming (quake 3 arena, etc), however the Robert Love patches are simpler, seem less intrusive, and I've had better luck with them on smp, highmem boxes.
(just IMHO) I like Andrew's patches on (up) workstations, and Robert's on (smp) servers, with some grey area of overlap -
I'm hardly the person to say, but the rml patches would seem more likely to go in sooner, if at all. I'd love to see both remain an option.
cu
jjs
Quoted 36 lines · J Sloan
------------------------------------------------------------------------
Subject: Re: low-latency patches
Date: Fri, 05 Oct 2001 23:51:55 -0700
From: J Sloan <[email protected]>
Organization: J S Concepts
To: Bob McElrath <[email protected]>
References: <[email protected]>Quoted 9 lines · Bob McElrath
It seems there are two low-latency projects out there. The one by Robert Love:
http://tech9.net/rml/linux/and the original one:
http://www.uow.edu.au/~andrewm/linux/schedlat.htmlCorrect 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?
Quoted 8 lines
My questions are:
1) Which of these two projects has better latency performance? Has anyone benchmarked them against each other?
2) Will either of these ever be merged into Linus' kernel (2.5?)
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 inarch/i386. Robert Love's patches would need some arch-specific asm...In my experience with them, the Andrew Morton patches provide a "smoother" interactive feel, great for things like online gaming (quake 3 arena, etc), however the Robert Love patches are simpler, seem less intrusive, and I've had better luck with them on smp, highmem boxes.
Quoted 8 lines
(just IMHO) I like Andrew's patches on (up) workstations, and Robert's on (smp) servers, with some grey area of overlap -
I'm hardly the person to say, but the rml patches would seem more likely to go in sooner, if at all. I'd love to see both remain an option.
The two patches are NOT mutually exclusive. Both can be used and are in some cases.
MontaVista is actively working on porting the patch you refer to as Robert Love's patch to most of the other archs. Which arch are you interested in?
George
Quoted 6 lines · george anzinger [[email protected]] wrote:
The two patches are NOT mutually exclusive. Both can be used and are in some cases.
MontaVista is actively working on porting the patch you refer to as Robert Love's patch to most of the other archs. Which arch are you interested in?
alpha. ;) I'd be happy to test early patches.
Cheers,
-- Bob
Bob McElrath ([email protected]) Univ. of Wisconsin at Madison, Department of Physics
Quoted 11 lines · Bob McElrath
Quoted 6 lines · george anzinger [[email protected]] wrote:
The two patches are NOT mutually exclusive. Both can be used and are in some cases.
MontaVista is actively working on porting the patch you refer to as Robert Love's patch to most of the other archs. Which arch are you interested in?
alpha. ;) I'd be happy to test early patches.
I am checking. Meanwhile, do you know alpha asm? The changes are relatively simple.
George
Quoted 6 lines · george anzinger [[email protected]] wrote:
Quoted 5 lines · Bob McElrath
Quoted 3 lines · george anzinger [[email protected]] wrote:
The two patches are NOT mutually exclusive. Both can be used and are in some cases.
Quoted 8 lines
Quoted 6 lines
Quoted 3 lines
MontaVista is actively working on porting the patch you refer to as Robert Love's patch to most of the other archs. Which arch are you interested in?
alpha. ;) I'd be happy to test early patches.
I am checking. Meanwhile, do you know alpha asm? The changes are relatively simple.
No, but I could probably figure it out (I know x86 asm, so might be able to convert the routines). I looked at it briefly and decided it would take me more than an hour to add alpha asm, so didn't do it immediately. ;)
If I hack something together (and it works), I'll send it to you.
Cheers,
-- Bob
Bob McElrath ([email protected]) Univ. of Wisconsin at Madison, Department of Physics