Date: Tue, 9 Jul 2002 10:05:58 -0400
To: zwane@linuxpower.ca, jamagallon@able.es
Cc: andrea@suse.de, linux-kernel@vger.kernel.org,
       lse-tech@lists.sourceforge.net
Subject: Re: pipe and af/unix latency differences between aa and jam on smp
Message-ID: <20020709140558.GA21293@rushmore>
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From: rwhron@earthlink.net
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> *Local* Communication latencies in microseconds - smaller is better

> kernel                          Pipe    AF/Unix
> -----------------------------  -------  -------
> 2.4.19-pre7-jam6                29.513   42.369
> 2.4.19-pre8-jam2                 7.697   15.274
> 2.4.19-pre8-jam2-nowuos          7.739   14.929

> (last line says that wake-up-sync is not responsible...)

> Main changes between first two were irqbalance and ide6->ide10.

The system is scsi only.  pre7-jam6 and pre8-jam2 .config's were 
identical.

> Could you try latest -rc1-aa2 ? It includes also irqbalance,

Based on Andrea'a diff logs, irqbalance appeared in 2.4.19pre10aa3.
There are small differences between the pre10-jam2 and aa irqbalance
patches.  One new datapoint with pre10-jam3:

*Local* Communication latencies in microseconds - smaller is better
-------------------------------------------------------------------
kernel                          Pipe    AF/Unix
-----------------------------  -------  -------
2.4.19-pre10-jam2                7.877   16.699
2.4.19-pre10-jam3               33.133   66.825
2.4.19-pre10-aa2                34.208   62.732
2.4.19-pre10-aa4                33.941   70.216
2.4.19-rc1-aa1-1g-nio           34.989   52.704

A config difference between pre10-jam2 and pre10-jam3 is:
CONFIG_X86_SFENCE=y	# pre10-jam2
pre10-jam2 was compiled with -Os and pre10-jam3 with -O2.

> Out of interest, is that a P4/Xeon?

Quad P3/Xeon 700 mhz with 1MB cache.

-- 
Randy Hron
http://home.earthlink.net/~rwhron/kernel/bigbox.html

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