Date: Tue, 19 Feb 2002 19:51:34 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Greg Lehey <grog@FreeBSD.ORG>, <arch@FreeBSD.ORG>, <jhb@FreeBSD.ORG> Subject: Re: buildworld comparison stable vs current Message-ID: <20020219194134.V1374-100000@gamplex.bde.org> In-Reply-To: <200202190534.g1J5Y7s58322@apollo.backplane.com>
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On Mon, 18 Feb 2002, Matthew Dillon wrote:
> The test boxes are DELL2550's, so 2xCPU (1.1GHz pentium III's),
> ECC memory, SCSI drives.
>
> A couple of things have become obvious during my own testing:
>
> * Context switching for every interrupt is expensive
>
> stable: 2467550 voluntary context switches (buildworld -j 10)
> current: 23879443 voluntary context switches (buildworld -j 10)
These mostly aren't for interrupts (unless they are for IPIs). I get:
393580 voluntary context switches
355294 involuntary context switches
for UP on an Athlon1600 (for a makeworld which took 1573 seconds in
-current), i.e., only 1/60 as many voluntary context switches. I think
most of them are for context switches to idle because Giant is held.
The idle process is more of a mistake than I first thought.
Bruce
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