From: Dario Faggioli <dfaggioli@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Cc: "Julien Grall" <julien.grall@arm.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Wei Liu" <wei.liu2@citrix.com>,
"Jan Beulich" <JBeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH] xen/sched: Re-position the domain_update_node_affinity() call during vcpu construction
Date: Tue, 11 Sep 2018 18:14:23 +0200 [thread overview]
Message-ID: <3684cff3526fc2adb160f6b072fac5eebb366944.camel@suse.com> (raw)
In-Reply-To: <1536242495-21173-1-git-send-email-andrew.cooper3@citrix.com>
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On Thu, 2018-09-06 at 15:01 +0100, Andrew Cooper wrote:
> alloc_vcpu()'s call to domain_update_node_affinity() has existed for
> a decade,
> but its effort is mostly wasted.
>
> alloc_vcpu() is called in a loop for each vcpu, bringing them into
> existence.
> The values of the affinity masks are still default, which is allcpus
> in
> general, or a processor singleton for pinned domains.
>
> Furthermore, domain_update_node_affinity() itself loops over all
> vcpus
> accumulating the masks, making it a scalability concern with large
> numbers of
> vcpus.
>
> Move it to be called once after all vcpus are constructed, which has
> the same
> net effect, but with fewer intermediate memory allocations and less
> cpumask
> arithmetic.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
>
Reviewed-by: Dario Faggioli <dfaggioli@suse.com>
Regards,
Dario
--
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Software Engineer @ SUSE https://www.suse.com/
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prev parent reply other threads:[~2018-09-11 16:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 14:01 [PATCH] xen/sched: Re-position the domain_update_node_affinity() call during vcpu construction Andrew Cooper
2018-09-07 8:33 ` Jan Beulich
2018-09-07 8:40 ` Wei Liu
2018-09-10 11:27 ` Julien Grall
2018-09-11 16:14 ` Dario Faggioli [this message]
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