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From: Paul Jackson <pj@sgi.com>
To: "Paul Menage" <menage@google.com>
Cc: a.p.zijlstra@chello.nl, maxk@qualcomm.com, mingo@elte.hu,
	tglx@linutronix.de, oleg@tv-sign.ru, rostedt@goodmis.org,
	linux-kernel@vger.kernel.org, rientjes@google.com
Subject: Re: [RFC/PATCH] cpuset: cpuset irq affinities
Date: Tue, 4 Mar 2008 00:51:48 -0600	[thread overview]
Message-ID: <20080304005148.4e6f1fe8.pj@sgi.com> (raw)
In-Reply-To: <6599ad830803032234v3bce2769l26379ea304fe885@mail.gmail.com>

Paul M wrote:
> I'm one such user who's been forced to add the mem_hardwall flag to
> get around the fact that exclusive and hardwall are controlled by the
> same flag. I keep meaning to send it in as a patch but haven't yet got
> round to it.

I made essentially the same mistake twice in the evolution of cpusets:
 1) overloading the cpu_exclusive flag to define sched domains, and
 2) overloading the mem_exclusive flag to define memory hardwalls.

I eventually reversed (1), with a deliberately incompatible change
(and you know how I resist those ;), creating a new 'sched_load_balance'
flag that controls the sched_domain partitioning, and removing any
affect that the cpu_exclusive flag has on this.

Perhaps the unfortunate interaction of mem_exclusive and hardwall is
destined to go the same path.  Thought the audience that is currently
using mem_exclusive for the purpose of hardwall enforcement of kernel
allocations might be broader than the specialized real-time audience
that was using cpu_exclusive for dynamic sched domain isolation, and so
we might not choose to just break compatibility in one shot, but rather
phase in your new flag, before, perhaps, in a later release, phasing
out the old hardwall overloading of the mem_exclusive flag.

(My primeval mistake was including the cpu_exclusive and mem_exclusive
flags in the original cpuset design; those two flags have given me
nothing but temptation to commit further design errors ;).


> Also, if you're using fake numa for memory isolation (which we're
> experimenting with) then the correlation between cpu placement and
> memory placement is much much weaker, or non-existent.

That might be a good answer to my asking where the beef was.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214

  reply	other threads:[~2008-03-04  6:52 UTC|newest]

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-27 22:21 [RFC/PATCH 0/4] CPUSET driven CPU isolation Peter Zijlstra
2008-02-27 22:21 ` [RFC/PATCH 1/4] sched: remove isolcpus Peter Zijlstra
2008-02-27 23:57   ` Max Krasnyanskiy
2008-02-28 10:19     ` Peter Zijlstra
2008-02-28 19:36       ` Max Krasnyansky
2008-02-27 22:21 ` [RFC/PATCH 2/4] cpuset: system sets Peter Zijlstra
2008-02-27 23:39   ` Paul Jackson
2008-02-28  1:53     ` Max Krasnyanskiy
2008-02-27 23:52   ` Max Krasnyanskiy
2008-02-28  0:11     ` Paul Jackson
2008-02-28  0:29       ` Steven Rostedt
2008-02-28  1:45         ` Max Krasnyanskiy
2008-02-28  3:41           ` Steven Rostedt
2008-02-28  4:58             ` Max Krasnyansky
2008-02-27 22:21 ` [RFC/PATCH 3/4] genirq: system set irq affinities Peter Zijlstra
2008-02-28  0:10   ` Max Krasnyanskiy
2008-02-28 10:19     ` Peter Zijlstra
2008-02-27 22:21 ` [RFC/PATCH 4/4] kthread: system set kthread affinities Peter Zijlstra
2008-02-27 23:38 ` [RFC/PATCH 0/4] CPUSET driven CPU isolation Max Krasnyanskiy
2008-02-28 10:19   ` Peter Zijlstra
2008-02-28 17:33     ` Max Krasnyanskiy
2008-02-28  7:50 ` Ingo Molnar
2008-02-28  8:08   ` Paul Jackson
2008-02-28  9:08     ` Ingo Molnar
2008-02-28  9:17       ` Paul Jackson
2008-02-28  9:32         ` David Rientjes
2008-02-28 10:12           ` David Rientjes
2008-02-28 10:26             ` Peter Zijlstra
2008-02-28 17:37             ` Paul Jackson
2008-02-28 21:24               ` David Rientjes
2008-02-28 22:46                 ` Paul Jackson
2008-02-28 23:00                   ` David Rientjes
2008-02-29  0:16                     ` Paul Jackson
2008-02-29  1:05                       ` David Rientjes
2008-02-29  3:34                         ` Paul Jackson
2008-02-29  4:00                           ` David Rientjes
2008-02-29  6:53                             ` Paul Jackson
2008-02-28 10:46         ` Ingo Molnar
2008-02-28 17:47           ` Paul Jackson
2008-02-28 20:11           ` Max Krasnyansky
2008-02-28 20:13             ` Paul Jackson
2008-02-28 20:26               ` Max Krasnyansky
2008-02-28 20:27                 ` Paul Jackson
2008-02-28 20:45                   ` Max Krasnyansky
2008-02-28 20:23       ` Max Krasnyansky
2008-02-28 17:48   ` Max Krasnyanskiy
2008-02-29  8:31   ` Andrew Morton
2008-02-29  8:36     ` Andrew Morton
2008-02-29  9:10     ` Ingo Molnar
2008-02-29 18:06       ` Max Krasnyanskiy
2008-02-28 12:12 ` Mark Hounschell
2008-02-28 19:57   ` Max Krasnyansky
2008-02-29 18:55 ` [RFC/PATCH] cpuset: cpuset irq affinities Peter Zijlstra
2008-02-29 19:02   ` Ingo Molnar
2008-02-29 20:52     ` Max Krasnyanskiy
2008-02-29 21:03       ` Peter Zijlstra
2008-02-29 21:20         ` Max Krasnyanskiy
2008-03-03 11:57           ` Peter Zijlstra
2008-03-03 17:36             ` Paul Jackson
2008-03-03 17:57               ` Peter Zijlstra
2008-03-03 18:10                 ` Paul Jackson
2008-03-03 18:18                   ` Peter Zijlstra
2008-03-04  7:35                     ` Paul Jackson
2008-03-04 11:06                       ` Peter Zijlstra
2008-03-04 19:52                         ` Max Krasnyanskiy
2008-03-05  1:11                           ` Paul Jackson
2008-03-05  8:37                             ` Peter Zijlstra
2008-03-05  8:50                               ` Ingo Molnar
2008-03-05 12:35                                 ` Paul Jackson
2008-03-05 12:43                                   ` Ingo Molnar
2008-03-05 17:44                                     ` Paul Jackson
2008-03-05 19:17                               ` Max Krasnyansky
2008-03-06 13:47                               ` Paul Jackson
2008-03-06 15:21                                 ` Peter Zijlstra
2008-03-07  3:40                                   ` Paul Jackson
2008-03-07  6:39                                     ` Paul Jackson
2008-03-07  8:47                                       ` Paul Menage
2008-03-07 14:57                                         ` Paul Jackson
2008-03-03 18:41                   ` Paul Menage
2008-03-03 18:52                     ` Paul Jackson
2008-03-04  5:26                       ` Paul Menage
2008-03-04  6:15                         ` Paul Jackson
2008-03-04  6:21                           ` Paul Menage
2008-03-04  6:26                             ` Paul Jackson
2008-03-04  6:34                               ` Paul Menage
2008-03-04  6:51                                 ` Paul Jackson [this message]
2008-02-29 20:55   ` Paul Jackson
2008-02-29 21:14     ` Peter Zijlstra
2008-02-29 21:29       ` Ingo Molnar
2008-02-29 21:32       ` Ingo Molnar
2008-02-29 21:42       ` Max Krasnyanskiy
2008-02-29 22:00         ` Paul Jackson
2008-02-29 21:53       ` Paul Jackson
2008-03-02  5:18   ` Christoph Hellwig

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