* Multi-threaded IO performance regression on 2.6 kernel?
@ 2005-07-21 7:48 Xie, Bill
2005-07-21 9:00 ` Miquel van Smoorenburg
0 siblings, 1 reply; 2+ messages in thread
From: Xie, Bill @ 2005-07-21 7:48 UTC (permalink / raw)
To: linux-kernel
All,
I am testing the multi-threaded IO performance on Opteron servers.
I use dd as the test tools. The single dd can reach 60MBps for single disk.
on 2.6.5 kernel, If dd numbers exceed the CPU numbers, vmstat bi reduced to 20MBps.
on 2.4.21 kernel, multi-threaded IO performance works fine, even I run 40 dd command at same time.
Does anybody experienced similar issue also?
Best Regards
Bill Xie
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Multi-threaded IO performance regression on 2.6 kernel?
2005-07-21 7:48 Multi-threaded IO performance regression on 2.6 kernel? Xie, Bill
@ 2005-07-21 9:00 ` Miquel van Smoorenburg
0 siblings, 0 replies; 2+ messages in thread
From: Miquel van Smoorenburg @ 2005-07-21 9:00 UTC (permalink / raw)
To: linux-kernel
In article <1784BBD8D1F15B4C9FB0F09F0A939F9001A3E463@SZEXMTA4.amd.com>,
Xie, Bill <bill.xie@amd.com> wrote:
>All,
>
>I am testing the multi-threaded IO performance on Opteron servers.
>
>I use dd as the test tools. The single dd can reach 60MBps for single disk.
>
>on 2.6.5 kernel, If dd numbers exceed the CPU numbers, vmstat bi reduced
>to 20MBps.
>
>on 2.4.21 kernel, multi-threaded IO performance works fine, even I run
>40 dd command at same time.
>
>Does anybody experienced similar issue also?
First, use a more recent kernel, 2.6.11.x or 2.6.12.x. Then try if
changing the I/O scheduler (/sys/block/sda/queue/scheduler) to
deadline or cfq makes a difference.
I'm using 2.6.11.x and the cfq scheduler on most servers right now.
Mike.
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