Re: Time sliced CFQ io scheduler

["Prakash K. Cheemplavam" <prakashkc@gmx.de>]

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Jens Axboe schrieb:
> On Fri, Dec 03 2004, Prakash K. Cheemplavam wrote:
> 
>>Jens Axboe schrieb:
>>
>>>On Thu, Dec 02 2004, Prakash K. Cheemplavam wrote:
>>>
>>
>>>>0  3   3080   2208   1156 817712    0    0  3592 75624 1326  2289  1 36  
>>>>0 63
>>>>0  3   3080   2664   1156 818240    0    0  5124 15692 1302   992  1 18  
>>>>0 81
>>>>0  3   3080   2580   1160 815832    0    0  4356 155792 1375  1064  1 39  
>>>>0 60
>>>>0  3   3080   2472   1160 817124    0    0  3076 100852 1345  1138  1 23  
>>>>0 76
>>>>2  4   3080   2836   1148 816228    0    0  3336 100412 1352  1379  1 47  
>>>>0 52
>>>>0  4   3080   2708   1144 815964    0    0  3844 48908 1343   871  1 25  
>>>>0 74
>>>>0  3   3080   2748   1152 815984    0    0  3332 71996 1338   843  1 27  
>>>>0 72
>>>
>>>
>>>Can you try with the patch that is in the parent of this thread? The
>>>above doesn't look that bad, although read performance could be better
>>>of course. But try with the patch please, I'm sure it should help you
>>>quite a lot.
>>>
>>
>>It actually got worse: Though the read rate seems accepteble, it is not, as 
>>interactivity is dead while writing. I cannot start porgrammes, other 
>>programmes which want to do i/o pretty much hang. This is only while 
>>writing. While reading there is no such problem.
> 
> 
> Interesting, thanks for testing. I'll run some tests here as well, so
> far only the cases mentioned yesterday have been tested.

BTW, in case it is misread: Above (except the io performance as such) is
no regression: The other schedulers behave the same on my system.


> You could try and bumb the slice period. But I'll experiment and see
> what happens. What is your test case?

[slice bumping] Uhm, is it doable via proc? I haven't seen text docs to
your patch and I am not good at kernel code ;-)

My test case was apkm's one: write 1gb continuesly and try to cat a
several gb big file to /dev/null. At the same time I checked starting
other apps/using my emial client...

For me the problem in mainline has been since quite some time...checked 
till kernel 2.6.7.

Prakash

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