On Mar 6, 2007, at 17:02 , Jonathan Corbet wrote:
Diego Gomez Deck <[EMAIL PROTECTED]> wrote:
The Squeak V4L code fallback to use read(), but the performance is
not
good.
I'm curious as to why that is. The read() interface is not the
preferred way to go, but it should not perform notably worse than
using
mmap().
When you mmap, the capturing does not block but works in parallel to
the processing, which should be significantly more effective, no?
Diego found more than 90% of time is spent in kernel land (not
captured by gprof). We now reach about 16 fps at 320x240. This
includes capturing, converting to 5-5-5 RGB which is Squeak's native
format, bitblt to Squeak's framebuffer, convert to 5-6-5 to match X,
then XShmPutImage. If the profiling is correct, then the first and
last step take 90%.
- Bert -
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