On Mar 20 2013, [email protected] 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 It appears I got wrong (outdated?)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 [email protected]) _______________________________________________ Kernelnewbies mailing list [email protected] http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
