From: "Richardson, Bruce" <bruce.richardson@intel.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] next releases
Date: Thu, 28 Aug 2014 09:22:27 +0000 [thread overview]
Message-ID: <59AF69C657FD0841A61C55336867B5B0343ECBD2@IRSMSX103.ger.corp.intel.com> (raw)
In-Reply-To: <2353283.PtiVvKdYNr@xps13>
> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> Sent: Thursday, August 28, 2014 10:06 AM
> To: Richardson, Bruce
> Cc: Cyril Chemparathy; dev@dpdk.org
> Subject: Re: [dpdk-dev] next releases
>
> 2014-08-28 08:41, Richardson, Bruce:
> > As for rte_rdtsc_precise, I'm not sure about its origins, but I'm
> > surprised to see that it does not correspond to the rdtscp instruction.
> > Can anyone else comment on this one? I would assume it's designed
> > to be used to get more accurate measurements of smaller blocks of
> > code that we want to benchmark, since rdtsc works best when timing
> > larger blocks (in terms of cycle counts, that is, not source lines :-) ).
>
> The good thing with git history (and well written commit logs) is that
> we can easily get such answer:
> http://dpdk.org/browse/dpdk/commit/?id=3314648f83c3dc06d7d9a
Indeed! I had mistakenly assumed that the function was older than the dpdk.org history. My bad on that one, and thanks for the link. :-)
>
> Bruce, do you know how rdtscp is supported across Intel processors?
Sorry, no I don't, and the instruction set manuals only say to check the relevant cpuid bit to see if it's supported. :-(. If the existing code works ok, there is probably no compelling reason to look to change it though.
>
> --
> Thomas
prev parent reply other threads:[~2014-08-28 9:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-25 17:15 Thomas Monjalon
2014-08-27 17:04 ` Cyril Chemparathy
2014-08-28 8:41 ` Richardson, Bruce
2014-08-28 9:06 ` Thomas Monjalon
2014-08-28 9:22 ` Richardson, Bruce [this message]
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