Date: Sun, 28 Jan 1996 18:13:13 +1100 From: Bruce Evans <bde@zeta.org.au> To: current@freebsd.org Subject: writes still slower than before recent vm changes Message-ID: <199601280713.SAA31441@godzilla.zeta.org.au>
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Bonnie reports that writes are 30%-50% slower than 2 weeks ago. However,
iozone reports that writes are slightly faster than 2 weeks ago. The
only significant difference between iozone writes and bonnie writes is
that iozone writes are page-aligned while bonnie writes aren't. Not
page aligning the buffers is stupid but shouldn't have such a large
penalty.
Bruce
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
before 128 1334 97.8 3095 42.8 1238 26.8 1507 97.8 3357 46.0 52.7 7.2
after(1) 128 1407 98.2 3104 37.7 1094 19.4 960 56.2 1664 22.4 55.0 6.9
after(2) 128 1399 97.7 3314 41.1 1444 27.9 1558 97.5 2379 30.0 59.3 7.5
before: kernel-Jan14
after(1): kernel-Jan20
after(2): kernel-Jan28 (after read-ahead fix) (current)
System:
CPU: i486DX (486-class CPU)
real memory = 16777216 (16384K bytes)
...
bt0: Bt44xC/ 0-(32bit) bus
(bt0:3:0): "QUANTUM XP34301 102C" type 0 fixed SCSI 2
sd1(bt0:3:0): Direct-Access 4106MB (8410200 512 byte sectors)
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