Max 50% usage on dual-core CPU

[Chris Stanley]

I'm working with ffmpeg which uses Pthreads-w32 in Windows XP Pro SP2.
I've used both Pthreads-w32 2.8.0 and 2.9.0 (which as far as I can tell
doesn't exist, but is bundled with the Celtic Druid ffmpeg binaries
nonetheless).

When using a single-core system (Celeron 2.5Ghz), everything is fine and
ffmpeg/Pthreads-w32 eagerly uses 97-99% of my CPU.  But when I move the
same code to a dual-core system (P4 3Ghz), it will never exceed exactly
50% of the CPU.  By default it uses both cores at about 20/30.  If I
change the affinity and restrict it to one core, then it uses the whole
thing but again won't exceed exactly 50% of the total CPU.  I get the
same results reading from and writing to a flash drive, so I don't think
it's an I/O bottleneck.

I'm posting this to the ffmpeg list as well, but it seems like this
could be something related to Pthreads-w32.  Does anyone have any
thoughts about what might be going on?

Thanks!

--

Chris Stanley

Systems Administrator          [hidden email]
                                Office 802-862-1645, x11
Center for Media & Democracy   Mobile [phone]
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[Chris Stanley]

I got a reply back from the other list and it was an ffmpeg issue with
an easy fix.  Sorry for the bother, thanks!

--

Chris Stanley

Systems Administrator          [hidden email]
                                Office 802-862-1645, x11
Center for Media & Democracy   Mobile [phone]
                                Fax    [phone]
294 North Winooski Ave         IM     ChrisStanleyCCTV
Burlington, VT 05401           http://www.cctv.org/


Chris Stanley wrote:

> I'm working with ffmpeg which uses Pthreads-w32 in Windows XP Pro SP2.
> I've used both Pthreads-w32 2.8.0 and 2.9.0 (which as far as I can tell
> doesn't exist, but is bundled with the Celtic Druid ffmpeg binaries
> nonetheless).
>
> When using a single-core system (Celeron 2.5Ghz), everything is fine and
> ffmpeg/Pthreads-w32 eagerly uses 97-99% of my CPU.  But when I move the
> same code to a dual-core system (P4 3Ghz), it will never exceed exactly
> 50% of the CPU.  By default it uses both cores at about 20/30.  If I
> change the affinity and restrict it to one core, then it uses the whole
> thing but again won't exceed exactly 50% of the total CPU.  I get the
> same results reading from and writing to a flash drive, so I don't think
> it's an I/O bottleneck.
>
> I'm posting this to the ffmpeg list as well, but it seems like this
> could be something related to Pthreads-w32.  Does anyone have any
> thoughts about what might be going on?
>
> Thanks!
>