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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: dev@dpdk.org, i.maximets@samsung.com, tiwei.bie@intel.com,
	zhihong.wang@intel.com, jasowang@redhat.com, stable@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2 0/4] vhost: add missing barriers, move prefetching
Date: Wed, 19 Dec 2018 10:50:42 -0500	[thread overview]
Message-ID: <20181219104947-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20181219082113.24455-1-maxime.coquelin@redhat.com>

On Wed, Dec 19, 2018 at 09:21:09AM +0100, Maxime Coquelin wrote:
> This series adds missing read barriers after reading avail index
> for split ring and desc flags for packed ring.
> 
> Also, it turns out that some descriptors prefetching are either
> badly placed, or useless, last part of the series fixes that.
> 
> With the series applied, I get between 0 and 4% gain depending
> on the benchmark (testpmd txonly/rxonly/io).
> 
> Thanks to Jason for reporting the missing read barriers.

Acked-by: Michael S. Tsirkin <mst@redhat.com>

But I wonder what effect this has on ARM where RMB isn't a NOP.
Ilya do you happen to have any data?

> Changes since v1:
> =================
> - Drop volatile removal patch (Ilya)
> - Improve commit messages for RMB patches (Ilya)
> 
> Maxime Coquelin (4):
>   vhost: enforce avail index and desc read ordering
>   vhost: enforce desc flags and content read ordering
>   vhost: prefetch descriptor after the read barrier
>   vhost: remove useless prefetch for packed ring descriptor
> 
>  lib/librte_vhost/virtio_net.c | 27 ++++++++++++++++++++++-----
>  1 file changed, 22 insertions(+), 5 deletions(-)
> 
> -- 
> 2.17.2

  parent reply	other threads:[~2018-12-19 15:50 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-19  8:21 Maxime Coquelin
2018-12-19  8:21 ` [dpdk-dev] [PATCH v2 1/4] vhost: enforce avail index and desc read ordering Maxime Coquelin
2018-12-19 15:47   ` Michael S. Tsirkin
2018-12-19 15:50     ` Maxime Coquelin
2018-12-19  8:21 ` [dpdk-dev] [PATCH v2 2/4] vhost: enforce desc flags and content " Maxime Coquelin
2018-12-19  8:21 ` [dpdk-dev] [PATCH v2 3/4] vhost: prefetch descriptor after the read barrier Maxime Coquelin
2018-12-19  8:21 ` [dpdk-dev] [PATCH v2 4/4] vhost: remove useless prefetch for packed ring descriptor Maxime Coquelin
2018-12-19 15:49   ` Michael S. Tsirkin
2018-12-19 15:50 ` Michael S. Tsirkin [this message]
2018-12-19 16:28   ` [dpdk-dev] [PATCH v2 0/4] vhost: add missing barriers, move prefetching Ilya Maximets
2018-12-20  4:39 ` Tiwei Bie
2018-12-20 18:19 ` Maxime Coquelin

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