Re: [PATCH 3/6] vhost: switch to use vhost_add_used_n()
From: Jason Wang <jasowang@redhat.com>
Date: 2013-08-20 02:36:23
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On 08/16/2013 05:56 PM, Michael S. Tsirkin wrote:
On Fri, Aug 16, 2013 at 01:16:27PM +0800, Jason Wang wrote:quoted
quoted
Let vhost_add_used() to use vhost_add_used_n() to reduce the code duplication. Signed-off-by: Jason Wang <jasowang@redhat.com>Does compiler inline it then? Reason I ask, last time I checked put_user inside vhost_add_used was much cheaper than copy_to_user inside vhost_add_used_n, so I wouldn't be surprised if this hurt performance. Did you check?
I run virtio_test but didn't see the difference. Did you mean the might_fault() in __copy_to_user()? So how about switch to use __put_user() if count is one in __vhost_add_used_n()?