From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: David Vrabel <david.vrabel@citrix.com>, konrad.wilk@oracle.com
Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
Subject: Re: [Xen-devel] [PATCH] xen/gntdev: Don't allocate struct gntdev_copy_batch on stack
Date: Tue, 19 Jan 2016 09:26:12 -0500 [thread overview]
Message-ID: <569E4784.10602@oracle.com> (raw)
In-Reply-To: <569CC84A.1000401@citrix.com>
On 01/18/2016 06:11 AM, David Vrabel wrote:
> On 15/01/16 19:43, Boris Ostrovsky wrote:
>> struct gntdev_copy_batch is over 1300 bytes in size, we shouldn't
>> put it on stack.
>>
>> Some compilers (e.g. 5.2.1) complain:
>> drivers/xen/gntdev.c: In function ‘gntdev_ioctl_grant_copy.isra.5’:
>> drivers/xen/gntdev.c:949:1: warning: the frame size of 1416 bytes
>> is larger than 1024 bytes [-Wframe-larger-than=]
> I thought I'd already reduced the size of this enough (from a batch size
> of 32 to 24) but this obviously isn't enough for 64-bit platforms.
>
> In the absence of any performance data on the best approach I would
> prefer just reducing the batch size to 16.
That would still leave us with over 900 bytes on the stack which I think
is rather high.
Do we expect this ioctl to be on some sort of a hot path?
-boris
next prev parent reply other threads:[~2016-01-19 14:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 19:43 [PATCH] xen/gntdev: Don't allocate struct gntdev_copy_batch on stack Boris Ostrovsky
2016-01-15 19:50 ` [Xen-devel] " Andrew Cooper
2016-01-15 19:53 ` Boris Ostrovsky
2016-01-15 19:53 ` [Xen-devel] " Boris Ostrovsky
2016-01-15 19:50 ` Andrew Cooper
2016-01-18 11:11 ` [Xen-devel] " David Vrabel
2016-01-19 14:26 ` Boris Ostrovsky
2016-01-19 14:26 ` Boris Ostrovsky [this message]
2016-01-19 14:31 ` David Vrabel
2016-01-19 14:31 ` [Xen-devel] " David Vrabel
2016-01-18 11:11 ` David Vrabel
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