Messages in this thread | | | Subject | Re: [PATCH net-next 1/3] vhost: generalize adding used elem | From | Jason Wang <> | Date | Fri, 14 Dec 2018 12:00:02 +0800 |
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On 2018/12/14 上午3:41, Michael S. Tsirkin wrote: > On Thu, Dec 13, 2018 at 06:10:20PM +0800, Jason Wang wrote: >> Use one generic vhost_copy_to_user() instead of two dedicated >> accessor. This will simplify the conversion to fine grain accessors. >> >> Signed-off-by: Jason Wang <jasowang@redhat.com> > > The reason we did it like this is because it was faster. > Want to try benchmarking before we change it?
Faster is a good side effect of such conversion. Otherwise we need two new fine grain memory accessor.
But, anyway, I can test its impact.
Thanks
> >> --- >> drivers/vhost/vhost.c | 11 +---------- >> 1 file changed, 1 insertion(+), 10 deletions(-) >> >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >> index 3a5f81a66d34..1c54ec1b82f8 100644 >> --- a/drivers/vhost/vhost.c >> +++ b/drivers/vhost/vhost.c >> @@ -2164,16 +2164,7 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq, >> >> start = vq->last_used_idx & (vq->num - 1); >> used = vq->used->ring + start; >> - if (count == 1) { >> - if (vhost_put_user(vq, heads[0].id, &used->id)) { >> - vq_err(vq, "Failed to write used id"); >> - return -EFAULT; >> - } >> - if (vhost_put_user(vq, heads[0].len, &used->len)) { >> - vq_err(vq, "Failed to write used len"); >> - return -EFAULT; >> - } >> - } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) { >> + if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) { >> vq_err(vq, "Failed to write used"); >> return -EFAULT; >> } >> -- >> 2.17.1
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