Re: [PATCH] libata: implement ata_qc_exec_internal()

[Tejun Heo <htejun@gmail.com>]

Tejun Heo wrote:
> Raz Ben-Jehuda(caro) wrote:
> 
>> does it solve the cpu usage ?
>>
>> On 11/28/05, Tejun Heo <htejun@gmail.com> wrote:
>>
>>> Each user libata internal commands initializes a qc, issues it, waits
>>> for its completion and checks for errors.  This patch factors internal
>>> command execution sequence into ata_qc_exec_internal().  The function
>>> also removes race condition between irq and timeout handling.
>>>
>>> Signed-off-by: Tejun Heo <htejun@gmail.com>
>>>
> 
> Hi, Raz.
> 
> It propabably has nothing to do with the cpu usage problem on piix you 
> reported.  I think you need to post more data to get people on the list 
> interested in your problem.  The followings may help.
> 
> 1. Please report exactly which kernel you're using and more information 
> on the hardware will also help.
> 
> 2. Don't use raid or any fs on it.  Just perform tests on raw /dev/sdx 
> devices.  Do something like 'time dd if=/dev/sdx of=/dev/zero bs=1M 
> count=1024' and report how much user/system time it uses.

Oops, count=1024 is way too small.  Do something like bs=1M count=1M or 
maybe count=10M.

> 
> 3. If above shows large system time consumption, build your kernel with 
> oprofile.  Start recording non-idle cpu cycles (the default) including 
> the kernel.  Repeat test in #2.  Dump oprofile result and post that here.
> 
> Hope it helps.
> 


-- 
tejun