Re: [patch] lowlatency patch for 2.4, lowlatency-2.4.0-test6-B5

From: Ingo Molnar (
Date: Thu Aug 03 2000 - 12:52:38 EST

On Thu, 3 Aug 2000, Jamie Lokier wrote:

> I notice you didn't include the ret_from_syscall race fix which shows
> up, rarely but it does. I think it was the last glitch seen in
> William Montgomery's tests with 2.2+lowlatency.

ok, i'll add that one too to the next version.

> Nice. That may be small enough to add into __get_user and __put_user.

i'm not sure. While they are legitimate scheduling points, but they are
too small i think to add a conditional schedule.

> As tweak you could use a short branch in libcalls.

what libcalls?

> Excessive. You don't need anything more than "pushl $1b; jmpl
> __cond_schedule" in the offline section, and let __cond_schedule do
> the register save/restore. That's 10 bytes, =3.1k.

you are right, i'll fix it for the next version, thanks for the

> (Now if only there was a way to convince the linker to use short jumps
> to long jumps per group of 256 bytes, it would be 7 bytes :-) But
> there isn't...)

10 bytes are good enough i think :-)


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