On 2016年11月10日 04:05, Michael S. Tsirkin wrote:
On Wed, Nov 09, 2016 at 03:38:33PM +0800, Jason Wang wrote:
This patch tries to utilize tuntap rx batching by peeking the tx
virtqueue during transmission, if there's more available buffers in
the virtqueue, set MSG_MORE flag for a hint for tuntap to batch the
packets. The maximum number of batched tx packets were specified
through a module parameter: tx_bached.
When use 16 as tx_batched:
When using
Pktgen test shows 16% on tx pps in guest.
Netperf test does not show obvious regression.
Why doesn't netperf benefit?
This is probably because the tests (4VCPU, 1queue, TCP, mlx4) does not
produce 100% stress on vhost thread. In pktgen test, 100% stress on
vhost thread is achieved easily.
For safety, 1 were used as the default value for tx_batched.
s/were used/is used/
Signed-off-by: Jason Wang <jasow...@redhat.com>
These tests unfortunately only run a single flow.
The concern would be whether this increases latency when
NIC is busy with other flows, so I think this is what
you need to test.
Multiple flows were tested too, no obvious improvement/regression were
found.
---
drivers/vhost/net.c | 15 ++++++++++++++-
drivers/vhost/vhost.c | 1 +
drivers/vhost/vhost.h | 1 +
3 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 5dc128a..51c378e 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -35,6 +35,10 @@ module_param(experimental_zcopytx, int, 0444);
MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
" 1 -Enable; 0 - Disable");
+static int tx_batched = 1;
+module_param(tx_batched, int, 0444);
+MODULE_PARM_DESC(tx_batched, "Number of patches batched in TX");
+
/* Max number of bytes transferred before requeueing the job.
* Using this limit prevents one virtqueue from starving others. */
#define VHOST_NET_WEIGHT 0x80000
I think we should do some tests and find a good default.
Ok, will test 4 and 32 to see if there's any difference. (Btw, 16 were
chosed since dpdk tends to batch 16 packet during TX).
Thanks
