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Message-ID: <555B5601.5020906@citrix.com>
Date: Tue, 19 May 2015 16:25:53 +0100
From: David Vrabel <david.vrabel@...rix.com>
To: Julien Grall <julien.grall@...rix.com>,
<xen-devel@...ts.xenproject.org>
CC: <ian.campbell@...rix.com>, <stefano.stabellini@...citrix.com>,
<tim@....org>, <linux-kernel@...r.kernel.org>,
David Vrabel <david.vrabel@...rix.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [Xen-devel] [RFC 16/23] xen/events: fifo: Make it running on
64KB granularity
On 14/05/15 18:00, Julien Grall wrote:
> Only use the first 4KB of the page to store the events channel info. It
> means that we will wast 60KB every time we allocate page for:
> * control block: a page is allocating per CPU
> * event array: a page is allocating everytime we need to expand it
>
> I think we can reduce the memory waste for the 2 areas by:
>
> * control block: sharing between multiple vCPUs. Although it will
> require some bookkeeping in order to not free the page when the CPU
> goes offline and the other CPUs sharing the page still there
>
> * event array: always extend the array event by 64K (i.e 16 4K
> chunk). That would require more care when we fail to expand the
> event channel.
I think you want an xen_alloc_page_for_xen() or similar to allocate a 4
KiB size/aligned block.
But as-is:
Reviewed-by: David Vrabel <david.vrabel@...rix.com>
David
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