[Angstrom-devel] [RFC] Using IOSCHED_NOOP as the default for linux-handhelds

[Paul Sokolovsky]

Hello,

Looking for what more stuff can be made modular, I'd like to make
IOSCHED_NOOP the default, builtin scheduler and make all other IO
schedulers modules. Current default is the anticipatory one. From
linux/block/Kconfig.iosched:

config IOSCHED_NOOP
        bool
        default y
        ---help---
          The no-op I/O scheduler is a minimal scheduler that does
basic merging
          and sorting. Its main uses include non-disk based block
devices like
          memory devices, and specialised software or hardware
environments
          that do their own scheduling and require only minimal
assistance from
          the kernel.

config IOSCHED_AS
        tristate "Anticipatory I/O scheduler"
        default y
        ---help---
          The anticipatory I/O scheduler is generally a good choice for
most
          environments, but is quite large and complex when compared to
the
          deadline I/O scheduler, it can also be slower in some cases
          especially some database loads.


IMHO, noop's description is good enough for builtin flash and flash
cards. I have no idea why IOSCHED_AS is used (pristine default is
IOSCHED_CFQ), but it is the same as used by linux-rp, so I assume
that's where it come from. So, I cc: Richard Purdie to ask if there're
good grounds for that and to draw attention that it's a chance to
recover some 5K for kernelspace-starving Z devices.


-- 
Best regards,
 Paul                          mailto:pmiscml at gmail.com