lkml.org 
[lkml]   [2001]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 2x Oracle slowdown from 2.2.16 to 2.4.4
Andi Kleen wrote:

> My understanding is that this is normally true for Oracle, but probably
> not for iozone so it would be better if you benchmarked random writes
> to an already allocated file.

You are correct that this is true for Oracle: we preallocate the file at db create
time, and we use O_DSYNC to avoid atime updates. The same is true for iozone: it
performs writes to all the blocks (creating the file and allocating blocks), then
rewrites all of the blocks. The write and rewrite times are measured and reported
in separate. Naturally, we only care about the rewrite times, and those are the
results I'm quoting when I casually use the term "writes". Also, we pass the "-o"
option to iozone, which causes it to open the file with O_SYNC (which on Linux is
really O_DSYNC), just like Oracle does. So, the mode I'm running iozone in really
does model Oracle i/o. Sorry if that wasn't clear.

Thanks,
Lance


begin:vcard
n:Larsh;Lance
x-mozilla-html:FALSE
url:http://www.oracle.com
org:Oracle Corporation;<img src=http://www.geocities.com/TheTropics/3068/oraani.gif>
version:2.1
email;internet:Lance.Larsh@oracle.com
title:Principal Software Engineer
adr;quoted-printable:;;500 Oracle Pkwy=0D=0AMS 401ip4;Redwood Shores;CA;94065;
x-mozilla-cpt:;6896
fn:Lance Larsh
end:vcard
\
 
 \ /
  Last update: 2005-03-22 12:57    [W:0.037 / U:3.988 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site