From: Con Kolivas <kernel@kolivas.org>
To: Nick Piggin <piggin@cyberone.com.au>
Cc: linux kernel mailing list <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] SMT Nice 2.6.4-rc1-mm1
Date: Mon, 1 Mar 2004 22:40:34 +1100 [thread overview]
Message-ID: <200403012240.34535.kernel@kolivas.org> (raw)
In-Reply-To: <4043205C.7050109@cyberone.com.au>
On Mon, 1 Mar 2004 10:37 pm, Nick Piggin wrote:
> Con Kolivas wrote:
> >On Mon, 1 Mar 2004 05:52 pm, Con Kolivas wrote:
> >>This patch provides full per-package priority support for SMT processors
> >>(aka pentium4 hyperthreading) when combined with CONFIG_SCHED_SMT.
> >
> >And here are some benchmarks to demonstrate what happens.
> >P4 3.06Ghz booted with bios HT off as UP (up), SMP with mm1(mm1), SMP with
> >mm1-smtnice(sn)
>
> Pretty impressive numbers.
>
> How does it go on the desktop when running mprime at nice +19?
> How much worse can latencies of the niced tasks become? Any idea?
Worst case scenario is easy to model; if a nice -19 task starts at exactly the
same time as a nice +19 task, the timeslices are 200 and 10ms. On
uniprocessor the nice+19 task will wait _at least_ 200 ms. On SMT nice SMP it
will be 200 - (200 * 15 / 100) so 170ms. That is of course worst case
scenario and still better than UP since the latency will be less, the task
will definitely start (interactive reinsertion wont affect it) and it will be
on a second runqueue.
Con
next prev parent reply other threads:[~2004-03-01 11:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-01 6:52 [PATCH] SMT Nice 2.6.4-rc1-mm1 Con Kolivas
2004-03-01 11:25 ` Con Kolivas
2004-03-01 11:37 ` Nick Piggin
2004-03-01 11:40 ` Con Kolivas [this message]
2004-03-01 11:46 ` Nick Piggin
2004-03-01 11:53 ` Con Kolivas
2004-03-01 11:45 ` Con Kolivas
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