KVM Archive on lore.kernel.org
 help / color / Atom feed
* [PATCH net-next] vhost_net: disable zerocopy by default
@ 2019-06-17  9:20 Jason Wang
  2019-06-17 14:43 ` Michael S. Tsirkin
  2019-06-17 20:58 ` David Miller
  0 siblings, 2 replies; 3+ messages in thread
From: Jason Wang @ 2019-06-17  9:20 UTC (permalink / raw)
  To: jasowang, mst, kvm, virtualization, netdev, linux-kernel; +Cc: huhai

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>
---
 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 2d9df786a9d3..21e0805e5e60 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -36,7 +36,7 @@
 
 #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");
-- 
2.18.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH net-next] vhost_net: disable zerocopy by default
  2019-06-17  9:20 [PATCH net-next] vhost_net: disable zerocopy by default Jason Wang
@ 2019-06-17 14:43 ` Michael S. Tsirkin
  2019-06-17 20:58 ` David Miller
  1 sibling, 0 replies; 3+ messages in thread
From: Michael S. Tsirkin @ 2019-06-17 14:43 UTC (permalink / raw)
  To: Jason Wang; +Cc: kvm, virtualization, netdev, linux-kernel, huhai

On Mon, Jun 17, 2019 at 05:20:54AM -0400, Jason Wang wrote:
> 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>

> ---
>  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 2d9df786a9d3..21e0805e5e60 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -36,7 +36,7 @@
>  
>  #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");
> -- 
> 2.18.1

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH net-next] vhost_net: disable zerocopy by default
  2019-06-17  9:20 [PATCH net-next] vhost_net: disable zerocopy by default Jason Wang
  2019-06-17 14:43 ` Michael S. Tsirkin
@ 2019-06-17 20:58 ` David Miller
  1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2019-06-17 20:58 UTC (permalink / raw)
  To: jasowang; +Cc: mst, kvm, virtualization, netdev, linux-kernel, huhai

From: Jason Wang <jasowang@redhat.com>
Date: Mon, 17 Jun 2019 05:20:54 -0400

> 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>

Applied, thanks Jason.

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, back to index

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-06-17  9:20 [PATCH net-next] vhost_net: disable zerocopy by default Jason Wang
2019-06-17 14:43 ` Michael S. Tsirkin
2019-06-17 20:58 ` David Miller

KVM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \
		kvm@vger.kernel.org kvm@archiver.kernel.org
	public-inbox-index kvm


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.kvm


AGPL code for this site: git clone https://public-inbox.org/ public-inbox