HEADS UP [Re: thread+preemption stability improvement]

[Scott Long]

All,

Initial testing of this patch looks very promising.  For those that
aren't comfortable with patching their sources by hand, note that it
was committed to CVS a few hours ago and should be showing up on CVSup
very shortly (rev 1.8 of sys/i386/i386/intr_machdep.c is what you want
if you are running i386).  Please go out and test this as much as 
possible so that we can determine if futher action is needed.

Scott

Robert Watson wrote:

> On Wed, 30 Jun 2004, John Baldwin wrote:
> 
> 
>>Try this patch.  It fixed all my lockups with xmms in KDE on Friday: 
> 
> 
> This patch causes my SMP and UP tests to succeed with PREEMPTION enabled,
> whereas before they rapidly hung.  On SMP I see a small (just under 1%) 
> but consistent improvement in query throughput with MySQL, and on UP I see
> a small (just under 1%) but inconsistent decrease in query throughput with
> MySQL.  The standard deviation on the UP case is almost the same size as
> the change, but in the SMP case it's 1/4-1/3 the size of the change, FWIW.
> 
> Can't speak to the latency as the test I'm currently running isn't very
> latency sensitive, but was very sensitive to the stability issue.  I think
> this patch is definitely worth committing ASAP :-).
> 
> Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
> robert at fledge.watson.org      Principal Research Scientist, McAfee Research
> 
> 
> 
>>--- //depot/projects/smpng/sys/i386/i386/intr_machdep.c	2004/07/02 20:28:06
>>+++ //depot/user/jhb/preemption/i386/i386/intr_machdep.c	2004/07/16 20:14:26
>>@@ -204,6 +204,8 @@
>> 		}
>> 		isrc->is_pic->pic_eoi_source(isrc);
>> 		error = 0;
>>+		/* XXX */
>>+		td->td_pflags &= ~TDP_OWEPREEMPT;
>> 		critical_exit();
>> 	} else {
>> 		/*
>>
>>-- 
>>John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
>>"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org
>>
> 
> 
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