From: George Dunlap <george.dunlap@citrix.com>
To: Dario Faggioli <dario.faggioli@citrix.com>,
xen-devel@lists.xenproject.org
Cc: George Dunlap <george.dunlap@eu.citrix.com>,
Juergen Gross <jgross@suse.com>,
Uma Sharma <uma.sharma523@gmail.com>
Subject: Re: [PATCH 13/16] xen: sched: allow for choosing credit2 runqueues configuration at boot
Date: Thu, 24 Mar 2016 12:36:42 +0000 [thread overview]
Message-ID: <56F3DF5A.8090206@citrix.com> (raw)
In-Reply-To: <20160318190538.8117.96025.stgit@Solace.station>
On 18/03/16 19:05, Dario Faggioli wrote:
> In fact, credit2 uses CPU topology to decide how to arrange
> its internal runqueues. Before this change, only 'one runqueue
> per socket' was allowed. However, experiments have shown that,
> for instance, having one runqueue per physical core improves
> performance, especially in case hyperthreading is available.
>
> In general, it makes sense to allow users to pick one runqueue
> arrangement at boot time, so that:
> - more experiments can be easily performed to even better
> assess and improve performance;
> - one can select the best configuration for his specific
> use case and/or hardware.
>
> This patch enables the above.
>
> Note that, for correctly arranging runqueues to be per-core,
> just checking cpu_to_core() on the host CPUs is not enough.
> In fact, cores (and hyperthreads) on different sockets, can
> have the same core (and thread) IDs! We, therefore, need to
> check whether the full topology of two CPUs matches, for
> them to be put in the same runqueue.
>
> Note also that the default (although not functional) for
> credit2, since now, has been per-socket runqueue. This patch
> leaves things that way, to avoid mixing policy and technical
> changes.
>
> Finally, it would be a nice feature to be able to select
> a particular runqueue arrangement, even when creating a
> Credit2 cpupool. This is left as future work.
>
> Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
> Signed-off-by: Uma Sharma <uma.sharma523@gmail.com>
Looks good, apart from the two errors Juergen pointed out. Thanks,
-George
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next prev parent reply other threads:[~2016-03-24 12:37 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-18 19:03 [PATCH 00/16] Fixes and improvement (including hard affinity!) for Credit2 Dario Faggioli
2016-03-18 19:04 ` [PATCH 01/16] xen: sched: fix locking when allocating an RTDS pCPU Dario Faggioli
2016-03-19 2:22 ` Meng Xu
2016-03-23 15:37 ` George Dunlap
2016-03-18 19:04 ` [PATCH 02/16] xen: sched: add .init_pdata hook to the scheduler interface Dario Faggioli
2016-03-22 8:08 ` Juergen Gross
2016-03-23 17:32 ` George Dunlap
2016-03-18 19:04 ` [PATCH 03/16] xen: sched: make implementing .alloc_pdata optional Dario Faggioli
2016-03-19 2:23 ` Meng Xu
2016-03-21 14:22 ` Jan Beulich
2016-03-23 17:36 ` George Dunlap
2016-03-24 9:43 ` Jan Beulich
2016-03-24 13:14 ` Dario Faggioli
2016-03-21 14:48 ` Juergen Gross
2016-03-21 15:07 ` Jan Beulich
2016-04-01 17:01 ` Dario Faggioli
2016-04-04 4:21 ` Juergen Gross
2016-04-04 6:13 ` Jan Beulich
2016-04-05 16:01 ` Dario Faggioli
2016-03-23 17:38 ` George Dunlap
2016-03-18 19:04 ` [PATCH 04/16] xen: sched: implement .init_pdata in all schedulers Dario Faggioli
2016-03-19 2:24 ` Meng Xu
2016-03-22 8:03 ` Juergen Gross
2016-03-23 17:46 ` George Dunlap
2016-03-18 19:04 ` [PATCH 05/16] xen: sched: move pCPU initialization in an helper Dario Faggioli
2016-03-23 17:51 ` George Dunlap
2016-03-23 18:09 ` George Dunlap
2016-03-24 13:21 ` Dario Faggioli
2016-03-18 19:04 ` [PATCH 06/16] xen: sched: prepare a .switch_sched hook for Credit1 Dario Faggioli
2016-03-18 19:04 ` [PATCH 07/16] xen: sched: prepare a .switch_sched hook for Credit2 Dario Faggioli
2016-03-18 19:04 ` [PATCH 08/16] " Dario Faggioli
2016-03-19 2:24 ` Meng Xu
2016-03-21 14:25 ` Jan Beulich
2016-03-18 19:05 ` [PATCH 09/16] xen: sched: close potential races when switching scheduler to CPUs Dario Faggioli
2016-03-19 2:25 ` Meng Xu
2016-03-23 19:05 ` George Dunlap
2016-04-05 16:26 ` Dario Faggioli
2016-04-06 15:51 ` Dario Faggioli
2016-03-24 12:14 ` George Dunlap
2016-04-05 17:37 ` Dario Faggioli
2016-04-06 16:21 ` Dario Faggioli
2016-03-18 19:05 ` [PATCH 10/16] xen: sched: improve credit2 bootparams' scope, placement and signedness Dario Faggioli
2016-03-21 14:51 ` Juergen Gross
2016-03-24 12:20 ` George Dunlap
2016-03-18 19:05 ` [PATCH 11/16] xen: sched: on Credit2, don't reprogram the timer if idle Dario Faggioli
2016-03-24 15:03 ` George Dunlap
2016-03-18 19:05 ` [PATCH 12/16] xen: sched: fix per-socket runqueue creation in credit2 Dario Faggioli
2016-03-24 12:24 ` George Dunlap
2016-03-18 19:05 ` [PATCH 13/16] xen: sched: allow for choosing credit2 runqueues configuration at boot Dario Faggioli
2016-03-22 7:46 ` Juergen Gross
2016-03-24 12:36 ` George Dunlap [this message]
2016-03-18 19:05 ` [PATCH 14/16] xen: sched: per-core runqueues as default in credit2 Dario Faggioli
2016-03-24 12:37 ` George Dunlap
2016-03-18 19:06 ` [PATCH 15/16] xen: sched: scratch space for cpumasks on Credit2 Dario Faggioli
2016-03-18 19:27 ` Andrew Cooper
2016-03-24 12:44 ` George Dunlap
2016-03-24 12:56 ` Andrew Cooper
2016-03-24 13:10 ` Dario Faggioli
2016-03-18 19:06 ` [PATCH 16/16] xen: sched: implement vcpu hard affinity in Credit2 Dario Faggioli
2016-03-24 15:42 ` George Dunlap
2016-04-05 16:50 ` Dario Faggioli
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