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From: Julien Grall <julien.grall@arm.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
	Xen-devel <xen-devel@lists.xen.org>
Cc: "Dario Faggioli" <dfaggioli@suse.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: Mon, 10 Sep 2018 12:27:03 +0100	[thread overview]
Message-ID: <21016b13-34eb-eef1-2646-d86901b0ae13@arm.com> (raw)
In-Reply-To: <1536242495-21173-1-git-send-email-andrew.cooper3@citrix.com>

Hi Andrew,

On 06/09/18 15:01, 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>

For Arm bits:

Acked-by: Julien Grall <julien.grall@arm.com>

Cheers,

-- 
Julien Grall

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  parent reply	other threads:[~2018-09-10 11:27 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 [this message]
2018-09-11 16:14 ` Dario Faggioli

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