[dpdk-dev] next releases

Richardson, Bruce bruce.richardson at intel.com
Thu Aug 28 11:22:27 CEST 2014

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> Sent: Thursday, August 28, 2014 10:06 AM
> To: Richardson, Bruce
> Cc: Cyril Chemparathy; dev at 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

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