From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH v8 1/3] eal/x86: run-time dispatch over memcpy
Date: Wed, 25 Oct 2017 11:00:00 +0200
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Cc: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>, "Richardson,
 Bruce" <bruce.richardson@intel.com>, dev@dpdk.org, "Lu,
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To: "Li, Xiaoyun" <xiaoyun.li@intel.com>
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25/10/2017 10:54, Li, Xiaoyun:
> > > > > > I think we should focus on micro-benchmark and find a
> > > > > > reasonnable threshold for a reasonnable drop tradeoff.
> > > > > >
> > > > > Sadly, it may not be that simple. What shows best performance for
> > > > > micro- benchmarks may not show the same effect in a real application.
> > > > >
> > > > > /Bruce
> > > >
> > > > Then how to measure the performance?
> > > >
> > > > And I cannot reproduce 15% drop on mellanox.
> > > > Could the person who tested 15% drop help to do test again with 1024
> > > > threshold and see if there is any improvement?
> > >
> > > As Bruce said, best performance on micro-benchmark may not show the
> > same effect in real applications.
> > > And I cannot reproduce the 15% drop.
> > > And I don't know if raising the threshold can improve the perf or not.
> > > Could the person who tested 15% drop help to do test again with 1024
> > threshold and see if there is any improvement?
> > 
> > As I already asked before - why not to make that threshold dynamic?
> > Konstantin
> > 
> I want to confirm that raising threshold is useful. Then can make it dynamic and set it very large as default.

You can confirm it with micro-benchmarks.