Date: Mon, 5 Mar 2001 15:24:44 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Chris Dillon <cdillon@wolves.k12.mo.us> Cc: "E.B. Dreger" <eddy+public+spam@noc.everquick.net>, <freebsd-hackers@FreeBSD.ORG> Subject: Re: Machines are getting too damn fast Message-ID: <200103052324.f25NOin45226@earth.backplane.com> References: <Pine.BSF.4.32.0103051443450.82525-100000@mail.wolves.k12.mo.us>
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:throughput. For example, on the PIII-850 (116MHz FSB and SDRAM, its
:overclocked) here on my desk with 256KB L2 cache:
:
:dd if=/dev/zero of=/dev/null bs=512k count=4000
:4000+0 records in
:4000+0 records out
:2097152000 bytes transferred in 8.229456 secs (254834825 bytes/sec)
:
:dd if=/dev/zero of=/dev/null bs=128k count=16000
:16000+0 records in
:16000+0 records out
:2097152000 bytes transferred in 1.204001 secs (1741819224 bytes/sec)
:
:Now THAT is a significant difference. :-)
Interesting. I get very different results with the 1.3 GHz P4. The
best I seem to get is 1.4 GBytes/sec. I'm not sure what the L2 cache
is on the box, but it's definitely a consumer model.
dd if=/dev/zero of=/dev/null bs=512k count=4000
2097152000 bytes transferred in 2.363903 secs (887156520 bytes/sec)
dd if=/dev/zero of=/dev/null bs=128k count=16000
2097152000 bytes transferred in 1.471046 secs (1425619621 bytes/sec)
If I use lower block sizes the syscall overhead blows up the
performance (it gets lower rather then higher). So I figure I don't
have as much L2 as on your system.
-Matt
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