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From: Wei Xu <wexu at redhat.com> Matthew found a roughly 40% tcp throughput regression with commit c67df11f(vhost_net: try batch dequing from skb array) as discussed in the following thread: https://www.mail-archive.com/netdev at vger.kernel.org/msg187936.html This is v3. v3: - move freeing skb from vhost to tun/tap recvmsg() to not confuse the callers. v2: - add Matthew as the

From: Wei Xu <wexu at redhat.com> Matthew found a roughly 40% tcp throughput regression with commit c67df11f(vhost_net: try batch dequing from skb array) as discussed in the following thread: https://www.mail-archive.com/netdev at vger.kernel.org/msg187936.html This is v3. v3: - move freeing skb from vhost to tun/tap recvmsg() to not confuse the callers. v2: - add Matthew as the

From: Wei Xu <wexu at redhat.com> Matthew found a roughly 40% tcp throughput regression with commit c67df11f(vhost_net: try batch dequing from skb array) as discussed in the following thread: https://www.mail-archive.com/netdev at vger.kernel.org/msg187936.html v4: - fix zero iov iterator count in tap/tap_do_read()(Jason) - don't put tun in case of EBADFD(Jason) - Replace

From: Wei Xu <wexu at redhat.com> Matthew found a roughly 40% tcp throughput regression with commit c67df11f(vhost_net: try batch dequing from skb array) as discussed in the following thread: https://www.mail-archive.com/netdev at vger.kernel.org/msg187936.html v4: - fix zero iov iterator count in tap/tap_do_read()(Jason) - don't put tun in case of EBADFD(Jason) - Replace

...akeup efficiency") even if we've stopped rx polling during handle_rx() since tx poll were still left in the waitqueue. Pktgen from a remote host to VM over mlx4 shows 5.5% improvements on rx PPS. (from 1.27Mpps to 1.34Mpps) Cc: Wei Xu <wexu at redhat.com> Cc: Matthew Rosato <mjrosato at linux.vnet.ibm.com> Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/vhost/net.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 68677d9..286c3e4 100644 --- a/drivers/vhost/net.c +++ b/drivers...

...akeup efficiency") even if we've stopped rx polling during handle_rx() since tx poll were still left in the waitqueue. Pktgen from a remote host to VM over mlx4 shows 5.5% improvements on rx PPS. (from 1.27Mpps to 1.34Mpps) Cc: Wei Xu <wexu at redhat.com> Cc: Matthew Rosato <mjrosato at linux.vnet.ibm.com> Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/vhost/net.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 68677d9..286c3e4 100644 --- a/drivers/vhost/net.c +++ b/drivers...

...g() supports accepting skb by msg_control after commit ac77cfd4258f ("tun: support receiving skb through msg_control"), the skb if presented should be freed within the function, otherwise it would be leaked. Signed-off-by: Wei Xu <wexu at redhat.com> Reported-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com> --- drivers/net/tun.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 6a7bde9..5563430 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -2067,14 +2067,17 @@ static int tun_recvmsg(str...

...a skb from the batched rx array while transmitting, which is simply done by moving checking the zero headcount a bit ahead. Also strengthen the small possibility of leak in case of recvmsg() fails by freeing the skb. Signed-off-by: Wei Xu <wexu at redhat.com> Reported-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com> --- drivers/vhost/net.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) v2: - add Matthew as the reporter, thanks matthew. - moving zero headcount check ahead instead of defer consuming skb due to jason and mst's comment. - add freei...

...a skb from the batched rx array while transmitting, which is simply done by moving checking the zero headcount a bit ahead. Also strengthen the small possibility of leak in case of recvmsg() fails by freeing the skb. Signed-off-by: Wei Xu <wexu at redhat.com> Reported-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com> --- drivers/vhost/net.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) v2: - add Matthew as the reporter, thanks matthew. - moving zero headcount check ahead instead of defer consuming skb due to jason and mst's comment. - add freei...

...during handle_rx() since tx poll >> were still left in the waitqueue. >> >> Pktgen from a remote host to VM over mlx4 shows 5.5% improvements on >> rx PPS. (from 1.27Mpps to 1.34Mpps) >> >> Cc: Wei Xu <wexu at redhat.com> >> Cc: Matthew Rosato <mjrosato at linux.vnet.ibm.com> >> Signed-off-by: Jason Wang <jasowang at redhat.com> >> --- > Now that vhost_poll_stop happens on data path > a lot, I'd say > if (poll->wqh) > there should be unlikely(). It has been there since 8241a1e466cd ("vhost_net...

...during handle_rx() since tx poll >> were still left in the waitqueue. >> >> Pktgen from a remote host to VM over mlx4 shows 5.5% improvements on >> rx PPS. (from 1.27Mpps to 1.34Mpps) >> >> Cc: Wei Xu <wexu at redhat.com> >> Cc: Matthew Rosato <mjrosato at linux.vnet.ibm.com> >> Signed-off-by: Jason Wang <jasowang at redhat.com> >> --- > Now that vhost_poll_stop happens on data path > a lot, I'd say > if (poll->wqh) > there should be unlikely(). It has been there since 8241a1e466cd ("vhost_net...

...e. This can be avoided by making sure we have got enough headcount before actually consuming a skb from the batched rx array while transmitting, which is simply done by moving checking the zero headcount a bit ahead. Signed-off-by: Wei Xu <wexu at redhat.com> Reported-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com> --- drivers/vhost/net.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 8d626d7..c7bdeb6 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -778,16 +778,6 @@ static void...

...adcount > > before actually consuming a skb from the batched rx array while > > transmitting, which is simply done by moving checking the zero > > headcount a bit ahead. > > > > Signed-off-by: Wei Xu <wexu at redhat.com> > > Reported-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com> > > --- > > drivers/vhost/net.c | 20 ++++++++++---------- > > 1 file changed, 10 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > > index 8d626d7..c7bdeb6 100644 > > --- a/drivers...

...adcount > > before actually consuming a skb from the batched rx array while > > transmitting, which is simply done by moving checking the zero > > headcount a bit ahead. > > > > Signed-off-by: Wei Xu <wexu at redhat.com> > > Reported-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com> > > --- > > drivers/vhost/net.c | 20 ++++++++++---------- > > 1 file changed, 10 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > > index 8d626d7..c7bdeb6 100644 > > --- a/drivers...

...s simply done by moving checking the zero >> headcount a bit ahead. >> >> Also strengthen the small possibility of leak in case of recvmsg() >> fails by freeing the skb. >> >> Signed-off-by: Wei Xu<wexu at redhat.com> >> Reported-by: Matthew Rosato<mjrosato at linux.vnet.ibm.com> >> --- >> drivers/vhost/net.c | 23 +++++++++++++---------- >> 1 file changed, 13 insertions(+), 10 deletions(-) >> >> v2: >> - add Matthew as the reporter, thanks matthew. >> - moving zero headcount check ahead instead of defer...

...s simply done by moving checking the zero >> headcount a bit ahead. >> >> Also strengthen the small possibility of leak in case of recvmsg() >> fails by freeing the skb. >> >> Signed-off-by: Wei Xu<wexu at redhat.com> >> Reported-by: Matthew Rosato<mjrosato at linux.vnet.ibm.com> >> --- >> drivers/vhost/net.c | 23 +++++++++++++---------- >> 1 file changed, 13 insertions(+), 10 deletions(-) >> >> v2: >> - add Matthew as the reporter, thanks matthew. >> - moving zero headcount check ahead instead of defer...

...e've stopped rx polling during handle_rx() since tx poll > were still left in the waitqueue. > > Pktgen from a remote host to VM over mlx4 shows 5.5% improvements on > rx PPS. (from 1.27Mpps to 1.34Mpps) > > Cc: Wei Xu <wexu at redhat.com> > Cc: Matthew Rosato <mjrosato at linux.vnet.ibm.com> > Signed-off-by: Jason Wang <jasowang at redhat.com> > --- Now that vhost_poll_stop happens on data path a lot, I'd say if (poll->wqh) there should be unlikely(). > drivers/vhost/net.c | 11 ++++++++--- > 1 file changed, 8 insertions(+)...

...t;) even if we've stopped rx polling during handle_rx(), tx poll were still left in the waitqueue. Pktgen from a remote host to VM over mlx4 on two 2.00GHz Xeon E5-2650 shows 11.7% improvements on rx PPS. (from 1.28Mpps to 1.44Mpps) Cc: Wei Xu <wexu at redhat.com> Cc: Matthew Rosato <mjrosato at linux.vnet.ibm.com> Signed-off-by: Jason Wang <jasowang at redhat.com> --- Changes from V1: - don't try to disable tx polling during start - poll tx on error unconditonally --- drivers/vhost/net.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/vhost/net.c b/drivers/v...

...ng a skb from the batched rx array while > transmitting, which is simply done by deferring it a moment later > in this patch. > > Signed-off-by: Wei Xu <wexu at redhat.com> Given the amount of effort Matthew has put into this, you definitely want Reported-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com> here. Let's give credit where credit is due. Thanks a lot Matthew! > --- > drivers/vhost/net.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index 8d626d7..e76535e 100644...

...msg_control after > commit ac77cfd4258f ("tun: support receiving skb through msg_control"), > the skb if presented should be freed within the function, otherwise it > would be leaked. > > Signed-off-by: Wei Xu <wexu at redhat.com> > Reported-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com> > --- > drivers/net/tun.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index 6a7bde9..5563430 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -...