----- Original Message ----- > > -----Original Message----- > > From: Jason Wang [mailto:jasowang@xxxxxxxxxx] > > Sent: Wednesday, December 16, 2020 1:57 PM > > To: wangyunjian <wangyunjian@xxxxxxxxxx> > > Cc: netdev@xxxxxxxxxxxxxxx; mst@xxxxxxxxxx; willemdebruijn kernel > > <willemdebruijn.kernel@xxxxxxxxx>; > > virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; > > Lilijun (Jerry) <jerry.lilijun@xxxxxxxxxx>; chenchanghu > > <chenchanghu@xxxxxxxxxx>; xudingke <xudingke@xxxxxxxxxx>; huangbin (J) > > <brian.huangbin@xxxxxxxxxx> > > Subject: Re: [PATCH net 2/2] vhost_net: fix high cpu load when sendmsg > > fails > > > > > > > > ----- Original Message ----- > > > > > > > > > > -----Original Message----- > > > > From: Jason Wang [mailto:jasowang@xxxxxxxxxx] > > > > Sent: Tuesday, December 15, 2020 12:10 PM > > > > To: wangyunjian <wangyunjian@xxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; > > > > mst@xxxxxxxxxx; willemdebruijn.kernel@xxxxxxxxx > > > > Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; Lilijun (Jerry) > > > > <jerry.lilijun@xxxxxxxxxx>; chenchanghu <chenchanghu@xxxxxxxxxx>; > > > > xudingke <xudingke@xxxxxxxxxx>; huangbin (J) > > > > <brian.huangbin@xxxxxxxxxx> > > > > Subject: Re: [PATCH net 2/2] vhost_net: fix high cpu load when sendmsg > > > > fails > > > > > > > > > > > > On 2020/12/15 上午9:48, wangyunjian wrote: > > > > > From: Yunjian Wang <wangyunjian@xxxxxxxxxx> > > > > > > > > > > Currently we break the loop and wake up the vhost_worker when > > sendmsg > > > > > fails. When the worker wakes up again, we'll meet the same error. > > > > > This > > > > > will cause high CPU load. To fix this issue, we can skip this > > > > > description by ignoring the error. When we exceeds sndbuf, the return > > > > > value of sendmsg is -EAGAIN. In the case we don't skip the > > > > > description > > > > > and don't drop packet. > > > > > > > > > > Signed-off-by: Yunjian Wang <wangyunjian@xxxxxxxxxx> > > > > > --- > > > > > drivers/vhost/net.c | 21 +++++++++------------ > > > > > 1 file changed, 9 insertions(+), 12 deletions(-) > > > > > > > > > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index > > > > > c8784dfafdd7..f966592d8900 100644 > > > > > --- a/drivers/vhost/net.c > > > > > +++ b/drivers/vhost/net.c > > > > > @@ -827,16 +827,13 @@ static void handle_tx_copy(struct vhost_net > > *net, > > > > struct socket *sock) > > > > > msg.msg_flags &= ~MSG_MORE; > > > > > } > > > > > > > > > > - /* TODO: Check specific error and bomb out unless ENOBUFS? > > */ > > > > > err = sock->ops->sendmsg(sock, &msg, len); > > > > > - if (unlikely(err < 0)) { > > > > > + if (unlikely(err == -EAGAIN)) { > > > > > vhost_discard_vq_desc(vq, 1); > > > > > vhost_net_enable_vq(net, vq); > > > > > break; > > > > > - } > > > > > > > > > > > > As I've pointed out in last version. If you don't discard descriptor, > > > > you > > > > probably > > > > need to add the head to used ring. Otherwise this descriptor will be > > > > always > > > > inflight that may confuse drivers. > > > > > > Sorry for missing the comment. > > > > > > After deleting discard descriptor and break, the next processing will be > > > the > > > same > > > as the normal success of sendmsg(), and vhost_zerocopy_signal_used() or > > > vhost_add_used_and_signal() method will be called to add the head to used > > > ring. > > > > It's the next head not the one that contains the buggy packet? > > In the modified code logic, the head added to used ring is exectly the > one that contains the buggy packet. -ENOTEA :( You're right, I misread the code. Thanks > > Thanks > > > > > Thanks > > > > > > > > Thanks > > > > > > > > > > > > > - if (err != len) > > > > > - pr_debug("Truncated TX packet: len %d != %zd\n", > > > > > - err, len); > > > > > + } else if (unlikely(err < 0 || err != len)) > > > > > > > > > > > > It looks to me err != len covers err < 0. > > > > > > OK > > > > > > > > > > > Thanks > > > > > > > > > > > > > + vq_err(vq, "Fail to sending packets err : %d, len : %zd\n", > > err, > > > > > +len); > > > > > done: > > > > > vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head); > > > > > vq->heads[nvq->done_idx].len = 0; > > > > > @@ -922,7 +919,6 @@ static void handle_tx_zerocopy(struct vhost_net > > > > *net, struct socket *sock) > > > > > msg.msg_flags &= ~MSG_MORE; > > > > > } > > > > > > > > > > - /* TODO: Check specific error and bomb out unless ENOBUFS? > > */ > > > > > err = sock->ops->sendmsg(sock, &msg, len); > > > > > if (unlikely(err < 0)) { > > > > > if (zcopy_used) { > > > > > @@ -931,13 +927,14 @@ static void handle_tx_zerocopy(struct > > vhost_net > > > > *net, struct socket *sock) > > > > > nvq->upend_idx = ((unsigned)nvq->upend_idx - 1) > > > > > % UIO_MAXIOV; > > > > > } > > > > > - vhost_discard_vq_desc(vq, 1); > > > > > - vhost_net_enable_vq(net, vq); > > > > > - break; > > > > > + if (err == -EAGAIN) { > > > > > + vhost_discard_vq_desc(vq, 1); > > > > > + vhost_net_enable_vq(net, vq); > > > > > + break; > > > > > + } > > > > > } > > > > > if (err != len) > > > > > - pr_debug("Truncated TX packet: " > > > > > - " len %d != %zd\n", err, len); > > > > > + vq_err(vq, "Fail to sending packets err : %d, len : %zd\n", > > err, > > > > > +len); > > > > > if (!zcopy_used) > > > > > vhost_add_used_and_signal(&net->dev, vq, head, 0); > > > > > else > > > > > > > > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
