lkml.org 
[lkml]   [2003]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 2.5.70-mm2 causes performance drop of random read O_DIRECT
Nick Piggin wrote:

> Steven Pratt wrote:
>
>> Nick Piggin wrote:
>>
>>> Steven Pratt wrote:
>>>
>>>> Starting in 2.5.70-mm2 and continuing in the mm tree, there is a
>>>> significant degrade in random read for block devices using
>>>> O_DIRECT. The drop occurs for all block sizes and ranges from
>>>> 30%-40. CPU usage is also lower although it may already be so low
>>>> as to be irrelavent.
>>>
>>> Hi Steven, this is quite likely to be an io scheduler problem.
>>> Is your test program rawread v2.1.5?
>>
>> This test was actually using 2.1.4, but the only difference in the
>> 2.1.5 version is a fix for the test label array for the aio versions
>> of the test. No functional change, just fixed the outputed test
>> description.
>>
>>> What is the command line you are using to invoke the program?
>>
>> rawread -t6 -p8 -m1 -d2 -s4096 -n65536 -l1 -z -x
>>
>> Which you can find if you follow either results link and look in the
>> benchmark directory where all raw benchmark out put is stored.
>
> OK thanks, I can now reproduce this! I'll work on it.

Looks like Andrew beat you to it. Both 2.5.70-mm7 and mm8 are back up
to the previous performance levels for random reads.

Steve

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:36    [W:0.049 / U:1.092 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site