| Re: seems to be a flaw in cfq [message #9189 is a reply to message #9183] |
Thu, 21 December 2006 12:16   |
Vasily Tarasov
Messages: 1345
Registered: January 2006
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Senior Member |
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Hello,
On 2.6.19 "buffered randread" bizarre behavior persists. So it was fixed
somewhere in 2.6.20... Can you give me a guess, what changes in 2.6.20
cause this fix? The point is that we want to port it back to 2.6.18
(rhel-5), if possible.
Thanks,
Vasily.
Jens Axboe wrote:
> On Thu, Dec 21 2006, Jens Axboe wrote:
>
>> On Thu, Dec 21 2006, Vasily Tarasov wrote:
>>
>>> Hello, Jens,
>>>
>>> Sorry for late answer.
>>> The situation is the following:
>>>
>>> direct seqread
>>> (2.6.18) - reproducable
>>> (2.6.20-rc1) - reproducable
>>> (2.6.20-rc1 + your fix) - not reproducable
>>>
>>> buffered randread
>>> (2.6.18) - reproducable
>>> (2.6.20-rc1) - not reproducable
>>> (2.6.20-rc1 + your fix) - not reproducable
>>>
>>> So the conclusion: problem with "direct seqread" is fixed by your patch
>>> (thanks!) and
>>> the problem with "buffered randread" was fixed in 2.6.19/2.6.20.
>>>
>> Perfect, explains why I didn't see much badness with buffered io on
>> 2.6.20-rc1'ish. Thanks for retesting and the initial report, the fix I
>> sent you is going upstream (sitting in the 'for-linus' branch awaiting a
>> pull) for 2.6.20-rc2.
>>
>
> Oh, Linus just pulled a few minutes ago, the fix is already upstream
> now.
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