Date: Thu, 15 Dec 2011 10:24:53 +0200 From: Ivan Klymenko <fidaj@ukr.net> To: Oliver Pinter <oliver.pntr@gmail.com> Cc: Tom Evans <tevans.uk@googlemail.com>, freebsd-stable@freebsd.org, Attilio Rao <attilio@freebsd.org>, Mitchell <george+freebsd@m5p.com>, "O. Hartmann" <ohartman@zedat.fu-berlin.de>, George Subject: Re: SCHED_ULE should not be the default Message-ID: <20111215102453.38580cf8@nonamehost.> In-Reply-To: <CAPjTQNEJDE17TLH-mDrG_-_Qa9R5N3mSeXSYYWtqz_DFidzYQw@mail.gmail.com> References: <4EE1EAFE.3070408@m5p.com> <CAJ-FndDniGH8QoT=kUxOQ%2BzdVhWF0Z0NKLU0PGS-Gt=BK6noWw@mail.gmail.com> <4EE2AE64.9060802@m5p.com> <4EE88343.2050302@m5p.com> <CAFHbX1%2B5PttyZuNnYot8emTn_AWkABdJCvnpo5rcRxVXj0ypJA@mail.gmail.com> <4EE933C6.4020209@zedat.fu-berlin.de> <CAPjTQNEJDE17TLH-mDrG_-_Qa9R5N3mSeXSYYWtqz_DFidzYQw@mail.gmail.com>
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=D0=92 Thu, 15 Dec 2011 03:05:12 +0100 Oliver Pinter <oliver.pntr@gmail.com> =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > On 12/15/11, O. Hartmann <ohartman@zedat.fu-berlin.de> wrote: > > On 12/14/11 18:54, Tom Evans wrote: > >> On Wed, Dec 14, 2011 at 11:06 AM, George Mitchell > >> <george+freebsd@m5p.com> wrote: > >>> > >>> Dear Secret Masters of FreeBSD: Can we have a decision on whether > >>> to change back to SCHED_4BSD while SCHED_ULE gets properly fixed? > >>> > >> > >> Please do not do this. This thread has shown that ULE performs > >> poorly in very specific scenarios where the server is loaded with > >> NCPU+1 CPU bound processes, and brought forward more complaints > >> about interactivity in X (I've never noticed this, and use a > >> FreeBSD desktop daily). > > > > I would highly appreciate a decission against SCHED_ULE as the > > default scheduler! SCHED_4BSD is considered a more mature entity > > and obviously it seems that SCHED_ULE needs some refinements to > > achieve a better level of quality. > > > >> > >> On the other hand, we have very many benchmarks showing how poorly > >> 4BSD scales on things like postgresql. We get much more load out of > >> our 8.1 ULE DB and web servers than we do out of our 7.0 ones. It's > >> easy to look at what you do and say "well, what suits my > >> environment is clearly the best default", but I think there are > >> probably more users typically running IO bound processes than CPU > >> bound processes. > > > > You compare SCHED_ULE on FBSD 8.1 with SCHED_4BSD on FBSD 7.0? > > Shouldn't you compare SCHED_ULE and SCHED_4BSD on the very same > > platform? > > > > Development of SCHED_ULE has been focused very much on DB like > > PostgreSQL, no wonder the performance benefit. But this is also a > > very specific scneario where SCHED_ULE shows a real benefit > > compared to SCHED_4BSD. > > > >> > >> I believe the correct thing to do is to put some extra > >> documentation into the handbook about scheduler choice, noting the > >> potential issues with loading NCPU+1 CPU bound processes. Perhaps > >> making it easier to switch scheduler would also help? > > > > Many people more experst in the issue than myself revealed some > > issues in the code of both SCHED_ULE and even SCHED_4BSD. It would > > be a pitty if all the discussions get flushed away like a > > "toilette-busisness" as it has been done all the way in the past. > > > > > > Well, I'd like to see a kind of "standardized" benchmark. Like on > > openbenchmark.org or at phoronix.com. I know that Phoronix' way of > > performing benchmarks is questionable and do not reveal much of the > > issues, but it is better than nothing. I'm always surprised by the > > worse performance of FreeBSD when it comes to threaded I/O. The > > differences between Linux and FreeBSD of the same development > > maturity are tremendous and scaring! > > > > It is a long time since I saw a SPEC benchmark on a FreeBSD driven > > HPC box. Most benchmark around for testing hardware are performed > > with Linux and Linux seems to make the race in nearly every > > scenario. It would be highly appreciable and interesting to see how > > Linux and FreeBSD would perform in SPEC on the same hardware > > platform. This is only an idea. Without a suitable benchmark with a > > codebase understood the discussion is in many aspects pointless > > -both ways. > > > > > >> > >> Cheers > >> > >> Tom > >> > >> References: > >> > >> http://people.freebsd.org/~kris/scaling/mysql-freebsd.png > >> http://suckit.blog.hu/2009/10/05/freebsd_8_is_it_worth_to_upgrade > >> _______________________________________________ > > > > >=20 > Hi! >=20 > Can you try with this settings: >=20 > op@opn ~> sysctl kern.sched. > kern.sched.cpusetsize: 8 > kern.sched.preemption: 0 > kern.sched.name: ULE > kern.sched.slice: 13 > kern.sched.interact: 30 > kern.sched.preempt_thresh: 224 > kern.sched.static_boost: 152 > kern.sched.idlespins: 10000 > kern.sched.idlespinthresh: 16 > kern.sched.affinity: 1 > kern.sched.balance: 1 > kern.sched.balance_interval: 133 > kern.sched.steal_htt: 1 > kern.sched.steal_idle: 1 > kern.sched.steal_thresh: 1 > kern.sched.topology_spec: <groups> > <group level=3D"1" cache-level=3D"0"> > <cpu count=3D"2" mask=3D"3">0, 1</cpu> > <children> > <group level=3D"2" cache-level=3D"2"> > <cpu count=3D"2" mask=3D"3">0, 1</cpu> > </group> > </children> > </group> > </groups> >=20 > Most of them from 7-STABLE settings, and with this, "works for me". > This an laptop with core2 duo cpu (with enabled powerd), and my kernel > config is here: > http://oliverp.teteny.bme.hu/freebsd/kernel_conf And you try to do like there http://www.youtube.com/watch?v=3D1CLCp-dqWu0 what would your the cursor mouse and Xorg NOT froze for a split second or more... And I'll see how really good your ULE ;)
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