Date: Thu, 18 Mar 2004 16:42:50 +0100
From: Andrea Arcangeli <andrea@suse.de>
To: Takashi Iwai <tiwai@suse.de>
Cc: "Marinos J. Yannikos" <mjy@geizhals.at>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org
Subject: Re: CONFIG_PREEMPT and server workloads
Message-ID: <20040318154250.GH2246@dualathlon.random>
References: <40591EC1.1060204@geizhals.at> <20040318060358.GC29530@dualathlon.random> <s5hlllycgz3.wl@alsa2.suse.de>
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On Thu, Mar 18, 2004 at 04:28:16PM +0100, Takashi Iwai wrote:
> the above one is the major source of RT-latency.
> only this oneliner will reduce more than 90% of RT-latencies.
> in my case with reiserfs, i got 0.4ms RT-latency with my test suite
> (with athlon 2200+).

cool ;)

> there is another point to be fixed in the reiserfs journal
> transaction.  then you'll get 0.1ms RT-latency without preemption.

[..]

> i think the first one is needed for preemptive kernel, too.
> with these patches, also 0.1-0.2ms RT-latency is achieved.

amazing.

And without those improvements you did, the worst case for 2.6 mainline
is 8msec, right?

thanks for the great work on lowlatency. I'm sure Andrew will pick those
improvements immediatly :).
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