From: Paul Emmerich <emmericp@net.in.tum.de>
To: dev@dpdk.org
Subject: Re: [dpdk-dev] TX performance regression caused by the mbuf cachline split
Date: Tue, 12 May 2015 01:18:31 +0200 [thread overview]
Message-ID: <555138C7.5010002@net.in.tum.de> (raw)
In-Reply-To: <55512DE5.7010800@net.in.tum.de>
Found a really simple solution that almost restores the original
performance: just add a prefetch on alloc. For some reason, I assumed
that this was already done since the troublesome commit I investigated
mentioned something about prefetching... I guess the commit referred to
the hardware prefetcher in the CPU.
Adding an explicit prefetch command in the mbuf alloc function gives a
throughput of 12.7/10.35 Mpps in my benchmark with the
simple/full-featured tx path.
DPDK 1.7.1 was at 14.1/10.7 Mpps. I guess I can live with that, since
I'm primarily interested in the full-featured path and the drop from
10.7 to ~10.4 was due to another change.
Patch: https://github.com/dpdk-org/dpdk/pull/2
I also sent an email to the mailing list.
I also think that the rx-path could also benefit from prefetching somewhere.
Paul
next prev parent reply other threads:[~2015-05-11 23:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-11 0:14 Paul Emmerich
2015-05-11 9:13 ` Luke Gorrie
2015-05-11 10:16 ` Paul Emmerich
2015-05-11 22:32 ` Paul Emmerich
2015-05-11 23:18 ` Paul Emmerich [this message]
2015-05-12 0:28 ` Marc Sune
2015-05-12 0:38 ` Marc Sune
2015-05-13 9:03 ` Ananyev, Konstantin
2016-02-15 19:15 ` Paul Emmerich
2016-02-19 12:31 ` Olivier MATZ
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