Re: [Xen-devel] Disk schedulers

[Paresh Nakhe <paresh.nakhe@xxxxxxxxx>]

On Fri, Feb 4, 2011 at 9:21 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

Please don't top post.

On Fri, 2011-02-04 at 15:34 +0000, Paresh Nakhe wrote:
> I was talking about dom0 here. We know that IO schedulers can be
> switched at runtime. They are not fixed at compile time configuration.
>
> After going through the code for IO schedulers, we realized that these
> were actually modules. If this is the case, we should be able to see
> them in /proc/modules which is not happening.

/proc/modules is core kernel functionality and I don't see how this
behaviour would differ from native.

Modules don't actually show up in /proc/modules until you load them.
This works for me.

quartz:~# modprobe deadline-iosched
quartz:~# cat /proc/modules
deadline_iosched 3671 0 - Live 0xf90e0000
nfsd 83866 11 - Live 0xf9098000
exportfs 3143 1 nfsd, Live 0xf8f08000
rtc_cmos 8147 0 - Live 0xf7c62000
rtc_core 14509 1 rtc_cmos, Live 0xf7c35000
rtc_lib 2428 1 rtc_core, Live 0xf7c04000

Ian.

root@paresh-hp:~# modprobe deadline-iosched
it is not showing the module after lsmod as in your case.

root@paresh-hp:~# rmmod deadline-iosched
ERROR: Module deadline_iosched does not exist in /proc/modules

(same for cfq-iosched)


root@paresh-hp:~# modprobe noop-iosched
FATAL: Module noop_iosched not found.


What could be the reason for this??

Anyways, if we modify the code, create a makefile, compile and load the module then there should not be any problem right??

Would it give an error saying that we are re-inserting an existing module??
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