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Date:      Wed, 27 Sep 2006 13:38:21 -0400
From:      John Baldwin <jhb@freebsd.org>
To:        Scott Long <scottl@samsco.org>
Cc:        Maxim Sobolev <sobomax@freebsd.org>, src-committers@freebsd.org, cvs-all@freebsd.org, cvs-src@freebsd.org
Subject:   Re: cvs commit: src/sys/i386/i386 local_apic.c
Message-ID:  <200609271338.22284.jhb@freebsd.org>
In-Reply-To: <451A9E1E.30601@samsco.org>
References:  <200609261608.k8QG8TYB044266@repoman.freebsd.org> <200609271117.25831.jhb@freebsd.org> <451A9E1E.30601@samsco.org>

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On Wednesday 27 September 2006 11:51, Scott Long wrote:
> John Baldwin wrote:
> > On Tuesday 26 September 2006 19:08, Maxim Sobolev wrote:
> > 
> >>John Baldwin wrote:
> >>
> >>>On Tuesday 26 September 2006 12:08, Maxim Sobolev wrote:
> >>>
> >>>>sobomax     2006-09-26 16:08:29 UTC
> >>>>
> >>>>  FreeBSD src repository
> >>>>
> >>>>  Modified files:        (Branch: RELENG_6)
> >>>>    sys/i386/i386        local_apic.c 
> >>>>  Log:
> >>>>  Revert 1.17.2.8, which reportedly causes problems on some hardware.
> >>>
> >>>The report I saw was that it broke ULE in general.  Are you going to 
> > 
> > revert it 
> > 
> >>>from amd64 as well?
> >>
> >>Yes, you are right - this is ULE specific bug. In fact, quick grep of 
> >>the ULE code reveals that it doesn't honor hlt_cpus_mask, so that the 
> >>problem is with ULE, not with the change in question.
> > 
> > 
> > Well, hlt_cpus_mask is really an x86-specific hack. :)
> > 
> 
> x86 and amd64, which represent about 95% of FreeBSD.

My point is that we need a notion of taking CPUs offline and online with 
scheudler hooks, instead of exporting a simple x86-specific bitmask.  Right 
now we don't notify the schedulers when a CPU goes offline so that they can 
try to do sensible things with pinned and bound threads, etc.  Instead, they 
just have to "notice" which is rediculously lame.

-- 
John Baldwin



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