linux-kernel - Re: [RFC/PATCH -v2] Add sysfs control to modify a user's cpu share

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Date:	Thu, 4 Oct 2007 10:54:51 +0200
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Mike Galbraith <efault@....de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	lkml <linux-kernel@...r.kernel.org>, maneesh@...ux.vnet.ibm.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	Sudhir Kumar <skumar@...ux.vnet.ibm.com>
Subject: Re: [RFC/PATCH -v2] Add sysfs control to modify a user's cpu share

> > Changelog since v1:
> > 1. Added a mutex to serialize directory creation/destruction for a user in
> >    sysfs
> > 2. Added a spinlock in the task_group structure to serialize writes to
> >    tg->shares.
> > 3. Removed /proc/root_user_cpu_shares.
> > 4. Added Documentation about the group scheduler.
> 
> thanks - I have added this to the queue.
> 
> i'm wondering about the following: could not (yet) existing UIDs be made 
> configurable too? I.e. if i do this in a bootup script:
> 
>   echo 2048 > /sys/kernel/uids/500/cpu_share
> 
> this should just work too, regardless of there not being any UID 500 
> tasks yet. Likewise, once configured, the /sys/kernel/uids/* directories 
> (with the settings in them) should probably not go away either.

Shouldn't that be done via uevents? E.g. UID x gets added to the sysfs tree,
generates a uevent and a script then figures out the cpu_share and sets it.
That way you also don't need to keep the directories. No?
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