From: "Jan Beulich" <JBeulich@suse.com>
To: George Dunlap <george.dunlap@citrix.com>
Cc: Dario Faggioli <dario.faggioli@citrix.com>,
Anshul Makkar <anshul.makkar@citrix.com>,
MengXu <mengxu@cis.upenn.edu>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH 2/3] xen: Have schedulers revise initial placement
Date: Mon, 01 Aug 2016 04:40:43 -0600 [thread overview]
Message-ID: <579F434B0200007800101346@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1468605722-24239-2-git-send-email-george.dunlap@citrix.com>
>>> On 15.07.16 at 20:02, <george.dunlap@citrix.com> wrote:
> The generic domain creation logic in
> xen/common/domctl.c:default_vcpu0_location() attempts to try to do
> initial placement load-balancing by placing vcpu 0 on the least-busy
> non-primary hyperthread available. Unfortunately, the logic can end
> up picking a pcpu that's not in the online mask. When this is passed
> to a scheduler such which assumes that the initial assignment is
> valid, it causes a null pointer dereference looking up the runqueue.
>
> Furthermore, this initial placement doesn't take into account hard or
> soft affinity, or any scheduler-specific knowledge (such as historic
> runqueue load, as in credit2).
>
> To solve this, when inserting a vcpu, always call the per-scheduler
> "pick" function to revise the initial placement. This will
> automatically take all knowledge the scheduler has into account.
>
> Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Should this and patch 3 be backported?
Jan
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next prev parent reply other threads:[~2016-08-01 10:40 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-15 18:02 [PATCH 1/3] xen: Some code motion to avoid having to do forward-declaration George Dunlap
2016-07-15 18:02 ` [PATCH 2/3] xen: Have schedulers revise initial placement George Dunlap
2016-07-15 18:07 ` Andrew Cooper
2016-07-16 14:12 ` Dario Faggioli
2016-07-18 18:10 ` Andrew Cooper
2016-07-18 18:55 ` Dario Faggioli
2016-07-18 21:36 ` Andrew Cooper
2016-07-19 7:14 ` Dario Faggioli
2016-07-18 10:28 ` Dario Faggioli
2016-07-25 11:17 ` George Dunlap
2016-07-25 14:36 ` Meng Xu
2016-07-26 9:17 ` Dario Faggioli
2016-07-25 14:35 ` Meng Xu
2016-08-01 10:40 ` Jan Beulich [this message]
2016-08-01 12:32 ` Dario Faggioli
2016-08-05 13:24 ` Jan Beulich
2016-08-05 14:09 ` Dario Faggioli
2016-08-05 14:44 ` Jan Beulich
2016-08-11 14:59 ` Dario Faggioli
2016-08-11 15:51 ` Andrew Cooper
2016-08-11 23:35 ` Dario Faggioli
2016-08-12 1:59 ` dependences for backporting to 4.6 [was: Re: [PATCH 2/3] xen: Have schedulers revise initial placement] Dario Faggioli
2016-08-12 13:53 ` Jan Beulich
2016-08-16 10:21 ` Dario Faggioli
2016-08-16 11:21 ` Jan Beulich
2016-08-12 8:58 ` dependences for backporting to 4.5 " Dario Faggioli
2016-07-15 18:02 ` [PATCH 3/3] xen: Remove buggy initial placement algorithm George Dunlap
2016-07-15 18:10 ` Andrew Cooper
2016-07-16 13:55 ` Dario Faggioli
2016-07-18 10:03 ` George Dunlap
2016-07-16 15:48 ` [PATCH 1/3] xen: Some code motion to avoid having to do forward-declaration Meng Xu
2016-07-18 9:58 ` Dario Faggioli
2016-07-18 10:06 ` George Dunlap
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