Message-ID: <1367315763.4616.93.camel@marge.simpson.net>
Subject: Re: [patch v7 0/21] sched: power aware scheduling
From: Mike Galbraith <bitbucket@online.de>
To: Ingo Molnar <mingo@kernel.org>
Cc: Len Brown <lenb@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Alex Shi <alex.shi@intel.com>, mingo@redhat.com, peterz@infradead.org,
        tglx@linutronix.de, akpm@linux-foundation.org, arjan@linux.intel.com,
        pjt@google.com, namhyung@kernel.org, morten.rasmussen@arm.com,
        vincent.guittot@linaro.org, gregkh@linuxfoundation.org,
        preeti@linux.vnet.ibm.com, viresh.kumar@linaro.org,
        linux-kernel@vger.kernel.org, len.brown@intel.com,
        rafael.j.wysocki@intel.com, jkosina@suse.cz, clark.williams@gmail.com,
        tony.luck@intel.com, keescook@chromium.org, mgorman@suse.de,
        riel@redhat.com, Linux PM list <linux-pm@vger.kernel.org>
Date: Tue, 30 Apr 2013 11:56:03 +0200
In-Reply-To: <1367315380.4616.91.camel@marge.simpson.net>
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On Tue, 2013-04-30 at 11:49 +0200, Mike Galbraith wrote: 
> On Tue, 2013-04-30 at 11:35 +0200, Mike Galbraith wrote: 
> > On Tue, 2013-04-30 at 10:41 +0200, Ingo Molnar wrote: 
> 
> > > Which are the workloads where 'powersaving' mode hurts workload 
> > > performance measurably?
> > 
> > Well, it'll lose throughput any time there's parallel execution
> > potential but it's serialized instead.. using average will inevitably
> > stack tasks sometimes, but that's its goal.  Hackbench shows it.
> 
> (but that consolidation can be a winner too, and I bet a nickle it would
> be for a socket sized pgbench run)

(belay that, was thinking of keeping all tasks on a single node, but
it'll likely stack the whole thing on a CPU or two, if so, it'll hurt)

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