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Max 50% usage on dual-core CPU
- From: Chris Stanley <cstanley at cctv dot org>
- To: pthreads-win32 at sourceware dot org
- Date: Mon, 12 Nov 2007 14:58:35 -0500
- Subject: Max 50% usage on dual-core CPU
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
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?
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