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SubjectRe: Hyperthreading performance oddities
(I'm aware that this could be considered thread necromancy, but I
haven't yet seen any indication that that is considered a bad thing in
these here parts; if it is, then I apologize, and upon being informed of
the fact will undertake to not commit such again.)

On 2/22/2008 5:06 AM, Frederik Deweerdt wrote:

> Hello Henk,
>
> On Fri, Feb 22, 2008 at 10:36:01AM +0100, belcampo wrote:
>
>> Kernel 2.6.22.9 smp hyperthreading
>> BENCHMARKs: VC: 334.042s VO: 0.053s A: 0.000s Sys: 4.049s = 338.143s
>> Kernel 2.6.22.9 nonsmp/hyperthreading
>> BENCHMARKs: VC: 262.008s VO: 0.031s A: 0.000s Sys: 3.528s = 265.567s
>> with 2.6.17 kernel smp/hyperthreading pentium-pro as CPU
>> BENCHMARKs: VC: 245.175s VO: 0.050s A: 0.000s Sys: 2.479s = 247.704s
>> with 2.6.17 kernel smp/hyperthreading pentium4 optimized kernel
>> BENCHMARKs: VC: 227.992s VO: 0.051s A: 0.000s Sys: 2.551s = 230.594s
>
> I'm not familiar with mplayer benchmarks, what do they actually
> measure?

I don't know if this discussion got continued privately, but on the
assumption that it didn't, I think I can give at least a basic answer to
this.

The VC: value is the amount of time spent in the video-codec code during
that run, the VO: value is the amount of time spent in the video-output
code, the A: is the amount of time spent in (ISTR) audio processing -
though whether codec or audio-output or audio filters etc. is unclear, I
remember there being separate values for those rather than their being
lumped under one header- and the Sys: value is I believe the amount of
time spent in system calls.

(For the record: I'm a long-time lurker and occasional, largely
non-code, contributor on the MPlayer development lists, but I've never
had occasion to look at the code behind or the logic involved in the
-benchmark output.)

--
Andrew Buehler


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