[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1355553634.4731.13.camel@marge.simpson.net>
Date: Sat, 15 Dec 2012 07:40:34 +0100
From: Mike Galbraith <bitbucket@...ine.de>
To: Vincent Guittot <vincent.guittot@...aro.org>
Cc: Alex Shi <alex.shi@...el.com>, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linaro-dev@...ts.linaro.org,
peterz@...radead.org, mingo@...nel.org, linux@....linux.org.uk,
pjt@...gle.com, santosh.shilimkar@...com, Morten.Rasmussen@....com,
chander.kashyap@...aro.org, cmetcalf@...era.com,
tony.luck@...el.com, preeti@...ux.vnet.ibm.com,
paulmck@...ux.vnet.ibm.com, tglx@...utronix.de,
len.brown@...el.com, arjan@...ux.intel.com,
amit.kucheria@...aro.org, viresh.kumar@...aro.org
Subject: Re: [RFC PATCH v2 3/6] sched: pack small tasks
On Fri, 2012-12-14 at 11:43 +0100, Vincent Guittot wrote:
> On 14 December 2012 08:45, Mike Galbraith <bitbucket@...ine.de> wrote:
> > On Fri, 2012-12-14 at 14:36 +0800, Alex Shi wrote:
> >> On 12/14/2012 12:45 PM, Mike Galbraith wrote:
> >> >> > Do you have further ideas for buddy cpu on such example?
> >> >>> > >
> >> >>> > > Which kind of sched_domain configuration have you for such system ?
> >> >>> > > and how many sched_domain level have you ?
> >> >> >
> >> >> > it is general X86 domain configuration. with 4 levels,
> >> >> > sibling/core/cpu/numa.
> >> > CPU is a bug that slipped into domain degeneration. You should have
> >> > SIBLING/MC/NUMA (chasing that down is on todo).
> >>
> >> Maybe.
> >> the CPU/NUMA is different on domain flags, CPU has SD_PREFER_SIBLING.
> >
> > What I noticed during (an unrelated) bisection on a 40 core box was
> > domains going from so..
> >
> > 3.4.0-bisect (virgin)
> > [ 5.056214] CPU0 attaching sched-domain:
> > [ 5.065009] domain 0: span 0,32 level SIBLING
> > [ 5.075011] groups: 0 (cpu_power = 589) 32 (cpu_power = 589)
> > [ 5.088381] domain 1: span 0,4,8,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68,72,76 level MC
> > [ 5.107669] groups: 0,32 (cpu_power = 1178) 4,36 (cpu_power = 1178) 8,40 (cpu_power = 1178) 12,44 (cpu_power = 1178)
> > 16,48 (cpu_power = 1177) 20,52 (cpu_power = 1178) 24,56 (cpu_power = 1177) 28,60 (cpu_power = 1177)
> > 64,72 (cpu_power = 1176) 68,76 (cpu_power = 1176)
> > [ 5.162115] domain 2: span 0-79 level NODE
> > [ 5.171927] groups: 0,4,8,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68,72,76 (cpu_power = 11773)
> > 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61,65,69,73,77 (cpu_power = 11772)
> > 2,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,66,70,74,78 (cpu_power = 11773)
> > 3,7,11,15,19,23,27,31,35,39,43,47,51,55,59,63,67,71,75,79 (cpu_power = 11770)
> >
> > ..to so, which looks a little bent. CPU and MC have identical spans, so
> > CPU should have gone away, as it used to do.
> >
> > 3.6.0-bisect (virgin)
> > [ 3.978338] CPU0 attaching sched-domain:
> > [ 3.987125] domain 0: span 0,32 level SIBLING
> > [ 3.997125] groups: 0 (cpu_power = 588) 32 (cpu_power = 589)
> > [ 4.010477] domain 1: span 0,4,8,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68,72,76 level MC
> > [ 4.029748] groups: 0,32 (cpu_power = 1177) 4,36 (cpu_power = 1177) 8,40 (cpu_power = 1178) 12,44 (cpu_power = 1178)
> > 16,48 (cpu_power = 1178) 20,52 (cpu_power = 1178) 24,56 (cpu_power = 1178) 28,60 (cpu_power = 1178)
> > 64,72 (cpu_power = 1178) 68,76 (cpu_power = 1177)
> > [ 4.084143] domain 2: span 0,4,8,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68,72,76 level CPU
> > [ 4.103796] groups: 0,4,8,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68,72,76 (cpu_power = 11777)
> > [ 4.124373] domain 3: span 0-79 level NUMA
> > [ 4.134369] groups: 0,4,8,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68,72,76 (cpu_power = 11777)
> > 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61,65,69,73,77 (cpu_power = 11778)
> > 2,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,66,70,74 ,78 (cpu_power = 11778)
> > 3,7,11,15,19,23,27,31,35,39,43,47,51,55,59,63,67,71,75,79 (cpu_power = 11780)
> >
>
> Thanks. that's an interesting example of a numa topology
>
> For your sched_domain difference,
> On 3.4, SD_PREFER_SIBLING was set for both MC and CPU level thanks to
> sd_balance_for_mc_power and sd_balance_for_package_power
> On 3.6, SD_PREFER_SIBLING is only set for CPU level and this flag
> difference with MC level prevents the destruction of CPU sched_domain
> during the degeneration
>
> We may need to set SD_PREFER_SIBLING for MC level
Ah, that explains oddity. (todo--).
Hm, seems changing flags should trigger a rebuild. (todo++,drat).
-Mike
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists