Re: [PATCH 3/6] vhost: switch to use vhost_add_used_n()

[Jason Wang]

On 08/16/2013 05:56 PM, Michael S. Tsirkin wrote:
> On Fri, Aug 16, 2013 at 01:16:27PM +0800, Jason Wang wrote:
>> > Let vhost_add_used() to use vhost_add_used_n() to reduce the code duplication.
>> > 
>> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> 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()?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/