Re: [Xen-devel] [RFC/RFT][PATCH 1 of 3] Move locking into pluggable schedulers.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2011-11-23 at 15:07 +0000, Dario Faggioli wrote:
> Pluggable schedulers' code knows what (and when) to lock better than
> generic code, let's delegate to them all the concurrency related issues.
> 
> Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> 
> diff -r 84b3e46aa7d2 xen/common/sched_credit.c
> --- a/xen/common/sched_credit.c       Wed Nov 23 12:03:37 2011 +0000
> +++ b/xen/common/sched_credit.c       Wed Nov 23 15:09:14 2011 +0100
> @@ -161,6 +161,7 @@ struct csched_dom {
>   * System-wide private data
>   */
>  struct csched_private {
> +    /* lock for the whole pluggable scheduler, nests inside cpupool_lock */
>      spinlock_t lock;
>      struct list_head active_sdom;
>      uint32_t ncpus;

Given that every scheduler plugin is going to need this lock perhaps it
could be provided globally (but still have the responsibility for using
it fall on the plugin)?

I was mainly thinking of the sedf case where you add and maintain the
whole structure for just that lock. Perhaps you have future plans which
involve having to do that anyway in which case maybe my suggestion
doesn't make sense.

Ian.



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