Date: Sat, 21 Aug 2004 18:11:46 +0000 (UTC) From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/geom/raid3 g_raid3.c g_raid3.h g_raid3_ctl.c src/sbin/geom/class/raid3 geom_raid3.c graid3.8 Message-ID: <200408211811.i7LIBk9v086394@repoman.freebsd.org>
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pjd 2004-08-21 18:11:46 UTC
FreeBSD src repository
Modified files:
sys/geom/raid3 g_raid3.c g_raid3.h g_raid3_ctl.c
sbin/geom/class/raid3 geom_raid3.c graid3.8
Log:
Implement new reading algorithm, which will use parity component for reading
as well, even if device is in complete state.
I observe 40% of speed-up with this option for random read operations,
but slowdown for sequential reads.
Basically, without this option reading from a RAID3 device built from 5
components (c0-c4) looks like this:
Request no. Used components
1 c0+c1+c2+c3
2 c0+c1+c2+c3
3 c0+c1+c2+c3
With the new feature:
Request no. Used components
1 c0+c1+c2+c3
2 (c1^c2^c3^c4)+c1+c2+c3
3 c0+(c0^c2^c3^c4)+c2+c3
4 c0+c1+(c0^c1^c3^c4)+c3
5 c0+c1+c2+(c0^c1^c2^c4)
6 c0+c1+c2+c3
[...]
Revision Changes Path
1.3 +14 -3 src/sbin/geom/class/raid3/geom_raid3.c
1.2 +16 -6 src/sbin/geom/class/raid3/graid3.8
1.7 +107 -95 src/sys/geom/raid3/g_raid3.c
1.2 +7 -2 src/sys/geom/raid3/g_raid3.h
1.2 +29 -5 src/sys/geom/raid3/g_raid3_ctl.c
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