From: Jason Wang jasowang@redhat.com
[ Upstream commit 098eadce3c622c07b328d0a43dda379b38cf7c5e ]
Vhost_net was known to suffer from HOL[1] issues which is not easy to fix. Several downstream disable the feature by default. What's more, the datapath was split and datacopy path got the support of batching and XDP support recently which makes it faster than zerocopy part for small packets transmission.
It looks to me that disable zerocopy by default is more appropriate. It cold be enabled by default again in the future if we fix the above issues.
[1] https://patchwork.kernel.org/patch/3787671/
Signed-off-by: Jason Wang jasowang@redhat.com Acked-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/vhost/net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index b40e8ded49c6..4d11152e60c1 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -35,7 +35,7 @@
#include "vhost.h"
-static int experimental_zcopytx = 1; +static int experimental_zcopytx = 0; module_param(experimental_zcopytx, int, 0444); MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;" " 1 -Enable; 0 - Disable");