On Wed, Mar 20, 2013 at 4:45 PM, Arlie Stephens <arlie@xxxxxxxxxxxx> wrote: > On Mar 20 2013, Valdis.Kletnieks@xxxxxx 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 It appears I got wrong (outdated?)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. Yeah, the "global" thing is just the system default. It's what newly created or discovered block devices will be assigned initially. > 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@xxxxxxxxxxxx) > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
