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Re: CONFIG_IOSCHED_* in m68k kernel



On Tue, May 19, 2009 at 06:28:51PM -0500, Lance Tagliapietra wrote:
> Hello,
> 
> I have observed that the m68k kernels available from [1] seem to have all the
> I/O Schedulers selected.  In other words all CONFIG_IOSCHED are being built
> in to the kernel (at least in the  2.6.26 and 2.6.28 available for the Amiga
> that I checked).  For example:
> 
> #
> # IO Schedulers
> #
> CONFIG_IOSCHED_NOOP=y
> CONFIG_IOSCHED_AS=y
> CONFIG_IOSCHED_DEADLINE=y
> CONFIG_IOSCHED_CFQ=y
> # CONFIG_DEFAULT_AS is not set
> # CONFIG_DEFAULT_DEADLINE is not set
> CONFIG_DEFAULT_CFQ=y
> # CONFIG_DEFAULT_NOOP is not set
> CONFIG_DEFAULT_IOSCHED="cfq"
> 
> I have done some checking, and have found that:
> a) CONFIG_IOSCHED_NOOP uses the least amount of RAM.
> b) CONFIG_IOSCHED_DEADLINE is the next 
> c) CONFIG_IOSCHED_AS and CONFIG_IOSCHED_CFQ are about the same and 
> more than NOOP or DEADLINE.
> d) The kernel default for m68k is CONFIG_DEFAULT_AS=y (per 2.6.29.1).
> 
> Is there a reason why all three are being built in to the m68k installer kernels?
> After some checking [2, among others] and testing, I would suggest the following:
> 
> #
> # IO Schedulers
> #
> CONFIG_IOSCHED_NOOP=y
> # CONFIG_IOSCHED_AS is not set
> # CONFIG_IOSCHED_DEADLINE is not set
> # CONFIG_IOSCHED_CFQ is not set
> # CONFIG_DEFAULT_AS is not set
> # CONFIG_DEFAULT_DEADLINE is not set
> # CONFIG_DEFAULT_CFQ is not set
> CONFIG_DEFAULT_NOOP=y
> CONFIG_DEFAULT_IOSCHED="noop"
> 
> As this configuration minimizes kernel footprint, the various other schedulers
> can be made modules with no change in the footprint, but is there value in 
> having them in the initrd for the installler?
> 
> Thoughts?

Only reason I know of is that it happens to be the Debian default. If 
other folks think it's worthwhile I can change this for m68k and see
if Debian wants to change it for all archs.

Peace,

Stephen

-- 
Stephen R. Marenka     If life's not fun, you're not doing it right!
<stephen@marenka.net>


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