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 kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
