Re: [PATCH V2 4/6] vhost_net: determine whether or not to use zerocopy at one time
From: Sergei Shtylyov <hidden>
Date: 2013-08-30 18:35:52
Also in:
kvm, lkml, virtualization
Hello. On 08/30/2013 08:29 AM, Jason Wang wrote:
Currently, even if the packet length is smaller than VHOST_GOODCOPY_LEN, if upend_idx != done_idx we still set zcopy_used to true and rollback this choice later. This could be avoided by determine zerocopy once by checking all conditions at one time before.
Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/vhost/net.c | 46 +++++++++++++++++++--------------------------- 1 files changed, 19 insertions(+), 27 deletions(-)
quoted hunk ↗ jump to hunk
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 8a6dd0d..ff60c2a 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c@@ -404,43 +404,35 @@ static void handle_tx(struct vhost_net *net) iov_length(nvq->hdr, s), hdr_size); break; } - zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN || - nvq->upend_idx != nvq->done_idx); + + zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN + && (nvq->upend_idx + 1) % UIO_MAXIOV != nvq->done_idx + && vhost_net_tx_select_zcopy(net);
Could you leave && on a first of two lines, matching the previous style?
/* use msg_control to pass vhost zerocopy ubuf info to skb */
if (zcopy_used) {
+ struct ubuf_info *ubuf;
+ ubuf = nvq->ubuf_info + nvq->upend_idx;
+
vq->heads[nvq->upend_idx].id = head;[...]
+ vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS; + ubuf->callback = vhost_zerocopy_callback; + ubuf->ctx = nvq->ubufs; + ubuf->desc = nvq->upend_idx; + msg.msg_control = ubuf; + msg.msg_controllen = sizeof(ubuf);
'sizeof(ubuf)' where 'ubuf' is a pointer? Are you sure it shouldn't be
'sizeof(*ubuf)'?
WBR, Sergei