From: arlie@worldash.org (Arlie Stephens)
To: kernelnewbies@lists.kernelnewbies.org
Subject: Linux elevators (Re: BFQ: simple elevator)
Date: Wed, 20 Mar 2013 16:45:28 -0700 [thread overview]
Message-ID: <20130320234528.GB11275@worldash.org> (raw)
In-Reply-To: <20699.1363821413@turing-police.cc.vt.edu>
On Mar 20 2013, Valdis.Kletnieks at vt.edu wrote:
> On Wed, 20 Mar 2013 16:05:09 -0700, Arlie Stephens said:
> > The ongoing thread reminds me of a simple question I've had since I
> > first read about linux' mutiple I/O schedulers. Why is the choice of
> > I/O scheduler global to the whole kernel, rather than per-device or
> > similar?
>
> They aren't global to the kernel.
Thanks for the correction. It appears I got wrong (outdated?)
information from some book on kernel development, or perhaps simply
misunderstood what I read.
When I tried the example you gave, I saw the same thing, even on
the older kernels I'm working with (2.6.32 in particular).
>
> On my laptop:
>
> # find /sys/devices/pci* -name 'scheduler' | xargs grep .
> /sys/devices/pci0000:00/0000:00:1f.2/ata1/host0/target0:0:0/0:0:0:0/block/sda/queue/scheduler:noop deadline [cfq]
> /sys/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sr0/queue/scheduler:noop deadline [cfq]
> # echo noop >| /sys/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sr0/queue/schedule
> # find /sys/devices/pci* -name 'scheduler' | xargs grep .
> /sys/devices/pci0000:00/0000:00:1f.2/ata1/host0/target0:0:0/0:0:0:0/block/sda/queue/scheduler:noop deadline [cfq]
> /sys/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sr0/queue/scheduler:[noop] deadline cfq
>
> I just changed the scheduler for the CD-ROM.
--
Arlie
(Arlie Stephens arlie at worldash.org)
next prev parent reply other threads:[~2013-03-20 23:45 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-20 15:54 BFQ: simple elevator Raymond Jennings
2013-03-20 19:24 ` Mulyadi Santosa
2013-03-20 21:03 ` Valdis.Kletnieks at vt.edu
2013-03-20 21:41 ` Raymond Jennings
2013-03-20 23:10 ` Valdis.Kletnieks at vt.edu
2013-03-20 23:37 ` Raymond Jennings
2013-03-21 9:13 ` Valdis.Kletnieks at vt.edu
2013-03-21 9:37 ` Raymond Jennings
2013-03-22 3:52 ` Mulyadi Santosa
2013-03-22 20:50 ` Raymond Jennings
2013-03-22 20:53 ` Raymond Jennings
2013-03-22 21:20 ` Valdis.Kletnieks at vt.edu
2013-03-23 0:05 ` Raymond Jennings
2013-03-23 16:42 ` Matthias Brugger
2013-03-25 19:15 ` Raymond Jennings
2013-03-25 22:27 ` Matthias Brugger
2013-03-25 22:29 ` Raymond Jennings
2013-03-23 1:42 ` Raymond Jennings
2013-03-23 14:38 ` Matthias Brugger
2013-03-25 18:19 ` Raymond Jennings
2013-03-20 23:05 ` Linux elevators (Re: BFQ: simple elevator) Arlie Stephens
2013-03-20 23:16 ` Valdis.Kletnieks at vt.edu
2013-03-20 23:45 ` Arlie Stephens [this message]
2013-03-21 1:00 ` Raymond Jennings
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