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

[Capn_Fish Zaurus]

On Feb 11, 2008 5:39 AM, pHilipp Zabel <philipp.zabel at gmail.com> wrote:

> On Feb 10, 2008 10:07 PM, Paul Sokolovsky <pmiscml at gmail.com> wrote:
> > 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.
>
> That sounds sane enough to me.
> Has anybody ever done benchmarks with the different schedulers on
> MTD/MMC/CF flash storage? Without knowing much about how AS or CFQ
> work, I'd even expect the noop scheduler to be the fastest here.
> Although, isn't there one zaurus that can boot directly from the
> internal microdrive?
>
> regards
> Philipp
>
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There are 3 Zaurii that have internal microdrives (the SL-C3x00 models), and
all can boot from them. Other models can boot from the external CF slot as
well.