Date: Thu, 11 Nov 2010 20:15:56 +0100
From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Mike Galbraith <efault@gmx.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC/RFT PATCH v3] sched: automated per tty task groups
Message-ID: <20101111191556.GA1564@arch.trippelsdorf.de>
References: <1287514410.7368.10.camel@marge.simson.net>
 <20101020025652.GB26822@elte.hu>
 <1287648715.9021.20.camel@marge.simson.net>
 <20101021105114.GA10216@Krystal>
 <1287660312.3488.103.camel@twins>
 <20101021162924.GA3225@redhat.com>
 <1288076838.11930.1.camel@marge.simson.net>
 <1288078144.7478.9.camel@marge.simson.net>
 <AANLkTimOJAv2uRfq4bW_QPngkGCmJDjNX5n_izpX=eB8@mail.gmail.com>
 <1289489200.11397.21.camel@maggy.simson.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <1289489200.11397.21.camel@maggy.simson.net>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1910
Lines: 65

On 2010.11.11 at 08:26 -0700, Mike Galbraith wrote:
> I _finally_ got back to this yesterday, and implemented your suggestion,
> though with a couple minor variations.  Putting the autogroup pointer in
> the signal struct didn't look right to me, so I plugged it into the task
> struct instead.  I also didn't refcount taskgroups, wanted the patchlet
> to be as self-contained as possible, so refcounted the autogroup struct
> instead.  I also left group movement on tty disassociation in place, but
> may nuke it.
...
> 
> With taskset -c 3 make -j 10 running..
> 
> taskset -c 3 ./wakeup-latency& sleep 30;killall wakeup-latency
> 
> without:
> maximum latency: 42963.2 ?s
> average latency: 9077.0 ?s
> missed timer events: 0
> 
> with:
> maximum latency: 4160.7 ?s
> average latency: 149.4 ?s
> missed timer events: 0

Just to add some data; here are the results from my machine (AMD 4
cores) running a -j4 kernel build, while I browsed the web:

1) perf sched record sleep 30

without:
total_wakeups: 44306
avg_wakeup_latency (ns): 36784
min_wakeup_latency (ns): 0
max_wakeup_latency (ns): 9378852

with:
total_wakeups: 43836
avg_wakeup_latency (ns): 67607
min_wakeup_latency (ns): 0
max_wakeup_latency (ns): 8983036

2) perf record -a -e sched:sched_switch -e sched:sched_wakeup sleep 10

without:
total_wakeups: 13195
avg_wakeup_latency (ns): 48484
min_wakeup_latency (ns): 0
max_wakeup_latency (ns): 8722497

with:
total_wakeups: 14106
avg_wakeup_latency (ns): 92532
min_wakeup_latency (ns): 20
max_wakeup_latency (ns): 5642393

So the avg_wakeup_latency nearly doubled with your patch, while the
max_wakeup_latency is lowered by a good amount.

-- 
Markus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/