[PATCH] vhost: fix unnecessary dirty page logging

[Xia, Chenbo]

> -----Original Message-----
> From: Ding, Xuan <xuan.ding at intel.com>
> Sent: Thursday, July 7, 2022 2:55 PM
> To: maxime.coquelin at redhat.com; Xia, Chenbo <chenbo.xia at intel.com>
> Cc: dev at dpdk.org; Hu, Jiayu <jiayu.hu at intel.com>; He, Xingguang
> <xingguang.he at intel.com>; Yang, YvonneX <yvonnex.yang at intel.com>; Jiang,
> Cheng1 <cheng1.jiang at intel.com>; Ding, Xuan <xuan.ding at intel.com>
> Subject: [PATCH] vhost: fix unnecessary dirty page logging
> 
> From: Xuan Ding <xuan.ding at intel.com>
> 
> The dirty page logging is only required in vhost enqueue direction for
> live migration. This patch removes the unnecessary dirty page logging
> in vhost dequeue direction. Otherwise, it will result in a performance
> drop. Some if-else judgements are also optimized to improve performance.
> 
> Fixes: 6d823bb302c7 ("vhost: prepare sync for descriptor to mbuf
> refactoring")
> Fixes: b6eee3e83402 ("vhost: fix sync dequeue offload")
> 
> Signed-off-by: Xuan Ding <xuan.ding at intel.com>
> ---

Reviewed-by: Chenbo Xia <chenbo.xia at intel.com>

Although it's late in release, we can consider to merge this as I see it impacts
the performance by 5%:
http://inbox.dpdk.org/dev/BYAPR11MB2711F13CDA2B0A4535A6591EFE839@BYAPR11MB2711.namprd11.prod.outlook.com/T/#t

But also, it will be good to know the performance issue is solved by sharing the
test results.

Thanks,
Chenbo