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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	huhai@kylinos.cn
Subject: Re: [PATCH net-next] vhost_net: disable zerocopy by default
Date: Mon, 17 Jun 2019 10:43:12 -0400	[thread overview]
Message-ID: <20190617104301-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20190617092054.12299-1-jasowang@redhat.com>

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

  reply	other threads:[~2019-06-17 14:43 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-17  9:20 [PATCH net-next] vhost_net: disable zerocopy by default Jason Wang
2019-06-17 14:43 ` Michael S. Tsirkin [this message]
2019-06-17 20:58 ` David Miller

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