PSN-L Email List Message
Subject: Re: Drop Outs
From: Brett Nordgren brett3nt@.............
Date: Tue, 25 Aug 2009 11:12:43 -0400
Hi Larry and Dick,
Adding more memory did help significantly after I went from 500MB to
1500MB. My own problem seems to relate to the fact that the screen
represented 24 hours of data at 200 samples per second. That is 17.28
million samples x the number of bytes stored per sample. The dropouts
still happen, but not nearly so often now.
Since then I have been doing some more checking with the Performance
Monitor (XP) and have a couple of observations. For me, dropouts mostly
happen when redisplaying the screen (F8), not so often when the screen
redraws itself at the end of the line, nor when generating the
gif's. Although virtual memory reads and writes go up a lot during a
redisplay, so far I haven't found any indication that memory is causing a
big problem. At times the swapping rates to virtual memory get quite high,
but as far as I can tell the machine appears to be handling it.
However..... During redisplay, the processor usage goes solidly to
100%. I am wondering how much processor effort it takes to filter 17
million data points? I had the feeling that the problem was in some way
related to filtering, but I never could really see what the relationship
was. I am pretty sure that when filtering is turned off the redisplay
dropouts disappear. I'll try to confirm that.
Hope there is something useful here.
Brett
At 06:02 PM 8/24/2009 -0700, you wrote:
>Hi Dick,
>
>Adding more RAM memory may help. It fixed Brett Nordgren's problem he
>report the other day.
>
>Regards,
>Larry Cochrane
>Webtronics
Watch our wiggles
http://bnordgren.org/seismo/gif_images.htm
or watch some very very good wiggles
http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/ANMO_24hr.html
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