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Re: [Discuss-gnuradio] Serious performance regression in Gnu Radio recen

From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] Serious performance regression in Gnu Radio recent
Date: Sun, 05 Feb 2012 17:07:34 -0500
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On 02/05/2012 04:44 PM, Marcus D. Leech wrote:
On 02/05/2012 04:08 PM, Tom Rondeau wrote:

So, what if it was your *own* commit that seemed to be causing a problem? Wouldn't that be embarrassing? I think so :-( :-(

commit 2a2411a598c222e2ef82b857c0b53e0a9d1daf3f
Author: Marcus Leech <address@hidden>
Date:   Sun Jan 15 23:49:52 2012 -0500

core: fix for off-by-one issue in strip chart. Increases buffer size for longer displays.

I have no idea why this should be a problem, the buffer-shifting for stripchart mode is all done on the C++ side, and the updates are done at a fairly lazy rate (a few Hz). So it's probably an issue on the Python side with bigger plot buffers. Perhaps there's some kind of N**2 scaling ugliness going on that wasn't immediately obvious to me when I did that patch.

I think ultimately, the plotting stuff has to move so that most of the computational stuff is done in C++ land, with only the thinnest pieces
  done on the Python side.

So performance degradation seems to scale with the size of OUTPUT_RECORD_SIZE in gr_oscope_guts.cc. This basically determines how big the messages are that are sent along to the plotter routines in Python, but the STRIPCHART routine uses it to store the strip-chart
  samples in.

Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

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