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From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: dev@dpdk.org, Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Hayato Momma <h-momma@ce.jp.nec.com>
Subject: Re: [dpdk-dev] [memnic PATCH 4/7] pmd: use compiler barrier
Date: Wed, 24 Sep 2014 17:18:09 +0200
Message-ID: <1855491.X6obi8qxOV@xps13> (raw)
In-Reply-To: <7F861DC0615E0C47A872E6F3C5FCDDBD011A9934@BPXM14GP.gisp.nec.co.jp>

2014-09-11 07:48, Hiroshi Shimamoto:
> x86 can keep store ordering with standard operations.

Are we sure it's always the case (including old 32-bit CPU)?
I would prefer to have a reference here. I know we already discussed
this kind of things but having a reference in commit log could help
for future discussions.

> Using memory barrier is much expensive in main packet processing loop.
> Removing this improves xmit/recv packet performance.
> 
> We can see performance improvements with memnic-tester.
> Using Xeon E5-2697 v2 @ 2.70GHz, 4 vCPU.
>  size |  before  |  after
>    64 | 4.18Mpps | 4.59Mpps
>   128 | 3.85Mpps | 4.87Mpps
>   256 | 4.01Mpps | 4.72Mpps
>   512 | 3.52Mpps | 4.41Mpps
>  1024 | 3.18Mpps | 3.64Mpps
>  1280 | 2.86Mpps | 3.15Mpps
>  1518 | 2.59Mpps | 2.87Mpps
> 
> Note: we have to take care if we use temporal cache.

Please, could you explain this last sentence?

Thanks
-- 
Thomas

  reply	other threads:[~2014-09-24 15:12 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-11  7:48 Hiroshi Shimamoto
2014-09-24 15:18 ` Thomas Monjalon [this message]
2014-09-25  0:35   ` Hiroshi Shimamoto

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