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From: Ilya Maximets <i.maximets@samsung.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
	Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: dev@dpdk.org, 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 19:28:07 +0300	[thread overview]
Message-ID: <9051b057-23df-78d4-04e0-6d02fadbd015@samsung.com> (raw)
In-Reply-To: <20181219104947-mutt-send-email-mst@kernel.org>

On 19.12.2018 18:50, Michael S. Tsirkin wrote:
> 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?

Hi.
My rough testing shows no significant performance difference on ARMv8.

> 
>> 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
> 
> 

  reply	other threads:[~2018-12-19 16:28 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 ` [dpdk-dev] [PATCH v2 0/4] vhost: add missing barriers, move prefetching Michael S. Tsirkin
2018-12-19 16:28   ` Ilya Maximets [this message]
2018-12-20  4:39 ` Tiwei Bie
2018-12-20 18:19 ` Maxime Coquelin

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