lkml.org 
[lkml]   [2007]   [May]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Preempt of BKL and with tickless systems
Lee Revell wrote:
> On 5/8/07, Bill Davidsen <davidsen@tmr.com> wrote:
>> I think I have a reasonable grip on the voluntary and full preempt
>> models, can anyone give me any wisdom on the preempt of the BKL? I know
>> what it does, the question is where it might make a difference under
>> normal loads. Define normal as servers and desktops.
>
> This was introduced by Ingo to solve a real problem that I found,
> where some codepath would hold the BKL for long enough to introduce
> excessive scheduling latencies - search list archive for details. But
> I don't remember the code path (scrolling the FB console? VT
> switching? reiser3? misc. ioctl()s?). Basically, taking the BKL
> disabled preemption which caused long latencies.
>
> It's certainly possible that whatever issue led to this was solved in
> another way since.
>
Anything is possible. I feel that using voluntary + bkl is probably good
for most servers, forced preempt for desktop, although it really doesn't
seem to do much beyond voluntary.

Thanks for the clarification.

--
Bill Davidsen <davidsen@tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-05-10 23:21    [W:0.052 / U:0.644 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site