Date: Sat, 28 Jan 2012 14:39:17 +0100 From: Attilio Rao <attilio@freebsd.org> To: Ryan Stone <rysto32@gmail.com>, Peter Holm <pho@freebsd.org>, Florian Smeets <flo@smeets.im> Cc: freebsd-hackers@freebsd.org Subject: Re: Kernel threads inherit CPU affinity from random sibling Message-ID: <CAJ-FndC1WHMyAXbT-rW=Ar%2BpspiwW%2B8cBF3OV4gMJssaO4UPUg@mail.gmail.com> In-Reply-To: <CAJ-FndD3366-uT191jMva3P-uL0DHi6nFeRfdsKA1hbJW7WqEA@mail.gmail.com> References: <CAFMmRNxF1uMOr39BbZkpPN=uM7G09dtcckAYw8ag6n6bi=FeOw@mail.gmail.com> <CAJ-FndDHsQRRNmrS7fsELEVohozWvvfaZ6eW_GipwHdjU9ZwxA@mail.gmail.com> <CAFMmRNyPkwx3hRtraq6QL64kibAeV3W23FE34T1oDnf9SVFOYg@mail.gmail.com> <CAJ-FndD3366-uT191jMva3P-uL0DHi6nFeRfdsKA1hbJW7WqEA@mail.gmail.com>
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2012/1/28 Attilio Rao <attilio@freebsd.org>: > 2012/1/28 Ryan Stone <rysto32@gmail.com>: >> On Fri, Jan 27, 2012 at 10:41 PM, Attilio Rao <attilio@freebsd.org> wrot= e: >>> I think what you found out is very sensitive. >>> However, the patch is not correct as you cannot call >>> cpuset_setthread() with thread_lock held. >> >> Whoops! =C2=A0I actually discovered that for myself and had already fixe= d >> it, but apparently I included an old version of the patch in the >> email. >> >>> Hence this is my fix: >>> http://www.freebsd.org/~attilio/cpuset_root.patch >> >> Oh, I do like this better. =C2=A0I tried something similar myself but >> abandoned it because I misread how sched_affinity() was implemented by >> 4BSD(I had gotten the impression that once TSF_AFFINITY is set it >> could never be cleared). > > Do you have a pathological test-case for it? Are you going to test the pa= tch? BTW, I've just now updated the patch in order to remove an added white line and s/priority/affinity in comments. Thanks, Attilio --=20 Peace can only be achieved by understanding - A. Einstein
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