Re: BFQ speed tests [was Re: [PATCH RFC - TAKE TWO - 00/12] New version of the BFQ I/O Scheduler]
From: Paolo Valente
Date: Wed Jun 04 2014 - 06:24:56 EST
Il giorno 04/giu/2014, alle ore 12:03, Pavel Machek <pavel@xxxxxx> ha scritto:
> Hi!
>
>> Should this attempt be useless as well, I will, if you do not mind, try by asking you more details about your system and reproducing your configuration as much as I can.
>>
>
> Try making BFQ the default scheduler. That seems to break it for me,
> when selected at runtime, it looks stable.
>
> Anyway, here are some speed tests. Background load:
>
> root@duo:/data/tmp# echo cfq > /sys/block/sda/queue/scheduler
> root@duo:/data/tmp# echo 3 > /proc/sys/vm/drop_caches
> root@duo:/data/tmp# cat /dev/zero > delme; cat /dev/zero > delme;cat
> /dev/zero > delme;cat /dev/zero > delme;cat /dev/zero > delme;cat
> /dev/zero > delme
>
> (Machine was running out of disk space.)
>
> (I alternate between cfq and bfq).
>
> Benchmark. I chose git describe because it is part of kernel build
> sometimes .. and I actually wait for that.
>
> pavel@duo:/data/l/linux-good$ time git describe
> warning: refname 'HEAD' is ambiguous.
> v3.15-rc8-144-g405dedd
>
> Unfortunately, results are not too good for BFQ. (Can you replicate
> the results?)
>
> # BFQ
> 10.24user 1.62system 467.02 (7m47.028s) elapsed 2.54%CPU
> # CFQ
> 8.55user 1.26system 69.57 (1m9.577s) elapsed 14.11%CPU
> # BFQ
> 11.70user 3.18system 1491.59 (24m51.599s) elapsed 0.99%CPU
> # CFQ, no background load
> 8.51user 0.75system 30.99 (0m30.994s) elapsed 29.91%CPU
> # CFQ
> 8.70user 1.36system 74.72 (1m14.720s) elapsed 13.48%CPU
>
Definitely bad, we are about to repeat the test …
Thanks,
Paolo
> Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
Paolo Valente
Algogroup
Dipartimento di Fisica, Informatica e Matematica
Via Campi, 213/B
41125 Modena - Italy
homepage: http://algogroup.unimore.it/people/paolo/
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