From: "Jan Beulich" <JBeulich@suse.com>
To: David Vrabel <david.vrabel@citrix.com>
Cc: xen-devel@lists.xenproject.org, Keir Fraser <keir@xen.org>,
Ian Campbell <ian.campbell@citrix.com>, Tim Deegan <tim@xen.org>
Subject: Re: [PATCHv2 5/5] evtchn: pad struct evtchn to 64 bytes
Date: Tue, 16 Jun 2015 10:22:43 +0100 [thread overview]
Message-ID: <5580070302000078000855BA@mail.emea.novell.com> (raw)
In-Reply-To: <1434383299-21833-6-git-send-email-david.vrabel@citrix.com>
>>> On 15.06.15 at 17:48, <david.vrabel@citrix.com> wrote:
> The number of struct evtchn in a page must be a power of two. Under
> some workloads performance is improved slightly by padding struct
> evtchn to 64 bytes (a cache line), thus putting the per-channel locks
> into their own cache line.
>
> This does not decrease the number of struct evtchn's per-page.
>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
> ---
> I'm not sure we actually want to do this. I think it would be better
> to pack the struct evtchn and use vmap to turn the pages into a linear
> array for quicker lookup.
But then you'd end up with two locks on one cache line again. I.e.
I can see the possible benefit of making the tree a linear table, but
I don't see how that eliminates the desire for the change here.
Jan
next prev parent reply other threads:[~2015-06-16 9:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 15:48 [PATCHv2 0/5] evtchn: Improve scalebility David Vrabel
2015-06-15 15:48 ` [PATCHv2 1/5] evtchn: factor out freeing an event channel David Vrabel
2015-06-15 15:48 ` [PATCHv2 2/5] evtchn: simplify port_is_valid() David Vrabel
2015-06-15 15:57 ` Ian Campbell
2015-06-15 15:59 ` David Vrabel
2015-06-15 16:09 ` Ian Campbell
2015-06-15 15:48 ` [PATCHv2 3/5] evtchn: use a per-event channel lock for sending events David Vrabel
2015-06-16 9:18 ` Jan Beulich
2015-06-16 9:34 ` David Vrabel
2015-06-16 9:51 ` Jan Beulich
2015-06-16 9:57 ` David Vrabel
2015-06-16 15:19 ` David Vrabel
2015-06-16 15:58 ` David Vrabel
2015-06-16 16:19 ` Jan Beulich
2015-06-16 16:39 ` David Vrabel
2015-06-17 7:05 ` Jan Beulich
2015-06-16 16:06 ` Jan Beulich
2015-06-15 15:48 ` [PATCHv2 4/5] evtchn: remove the locking when unmasking an event channel David Vrabel
2015-06-16 9:19 ` Jan Beulich
2015-06-16 9:40 ` David Vrabel
2015-06-15 15:48 ` [PATCHv2 5/5] evtchn: pad struct evtchn to 64 bytes David Vrabel
2015-06-16 9:22 ` Jan Beulich [this message]
2015-06-16 11:14 ` Julien Grall
2015-06-16 11:59 ` Jan Beulich
2015-06-16 12:57 ` Julien Grall
2015-06-16 13:13 ` David Vrabel
2015-06-16 13:27 ` Julien Grall
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