Date: Fri, 9 Dec 2011 16:17:33 +0100 From: Attilio Rao <attilio@freebsd.org> To: George Mitchell <george+freebsd@m5p.com> Cc: freebsd-stable@freebsd.org Subject: Re: SCHED_ULE should not be the default Message-ID: <CAJ-FndDniGH8QoT=kUxOQ%2BzdVhWF0Z0NKLU0PGS-Gt=BK6noWw@mail.gmail.com> In-Reply-To: <4EE1EAFE.3070408@m5p.com> References: <4EE1EAFE.3070408@m5p.com>
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2011/12/9 George Mitchell <george+freebsd@m5p.com>: > dnetc is an open-source program from http://www.distributed.net/. =C2=A0I= t > tries a brute-force approach to cracking RC4 puzzles and also computes > optimal Golomb rulers. =C2=A0It starts up one process per CPU and runs at > nice 20 and is, for all intents and purposes, 100% compute bound. > > Here is what happens on my system, running 9.0-PRERELEASE, with and > without dnetc running, with SCHED_ULE and SCHED-4BSD, when I run the > command: > > time make buildkernel KERNCONF=3DWONDERLAND > > (I get similar results on 8.x as well.) > > SCHED_4BSD, dnetc not running: > 1329.715u 123.739s 24:47.95 97.6% =C2=A0 =C2=A0 =C2=A0 6310+1987k 11233+1= 1098io 419pf+0w > > SCHED_4BSD, dnetc running: > 1329.364u 115.158s 26:14.83 91.7% =C2=A0 =C2=A0 =C2=A0 6325+1987k 10912+1= 1060io 393pf+0w > > SCHED_ULE, dnetc not running: > 1357.457u 121.526s 25:20.64 97.2% =C2=A0 =C2=A0 =C2=A0 6326+1990k 11234+1= 1149io 419pf+0w > > SCHED_ULE, dnetc running: > Still going after seven and a half hours of clock time, up to > compiling netgraph/bluetooth. =C2=A0(Completed in another five minutes > after stopping dnetc so I could write this message in a reasonable > amount of time.) > > Not everybody runs this sort of program, but there are plenty of > similar projects out there, and people who try to participate in > them will be mightily displeased with their FreeBSD systems when > they do. =C2=A0Is there some case where SCHED_ULE exhibits significantly > better performance than SCHED_4BSD? =C2=A0If not, I think SCHED-4BSD > should remain the default GENERIC configuration until this is fixed. Hi George, are you interested in exploring more the case with SCHED_ULE and dnetc? More precisely I'd be interested in KTR traces. To be even more precise: With a completely stable GENERIC configuration (or otherwise please post your kernel config) please add the following: options KTR options KTR_ENTRIES=3D262144 options KTR_COMPILE=3D(KTR_SCHED) options KTR_MASK=3D(KTR_SCHED) While you are in the middle of the slow-down (so once it is well established) please do: # sysclt debug.ktr.cpumask=3D"" In the end go with: # ktrdump -ctf > ktr-ule-problem.out and send the file to this mailing list. Thanks, Attilio --=20 Peace can only be achieved by understanding - A. Einstein
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