Mikrotron eosens TS3, Руководство пользователя, Страница: 115 / 120

TS3 User Manual
page 106
Reserving Memory for Fas M otion
FasMotion r eserves some amount of PC memory when it starts. The default values is 200 “bu ff ers”,
which translates to about 1GB. On systems that have less than the 4GB recommended minimum
installed memory, this value may be too high, while on systems with 6GB or 8GB of installed
memory, the value may be bumped up for be tt er performance. The argument for memory allocation
is -n
x,
where
x,
represents the number of bu ff ers (about 5MB each) to be used.
Examples:
To lower the memory allocation
t o 500MB:
“...\FasMotion\ F asMotion. e xe” -n 100
To increase memory allocation t o 1.5GB
“...\FasMotion\ F asMotion. e xe” -n 300
Note: 300 bu ff ers is the maximum Windows will allow.
Using Multiple s witches:
If you are adding the -n switch, you will likely be using the -s “stats” switch as well. Multiple
s witches may be used, separated only by a space (the order does not ma tt er):
“...\FasMotion\ F asMotion. e xe” -n 300 -s
In “Figure 10-10: FasMotion Shor t cut” notice the r e are three memory arguments:
“...\FasMotion\ F asMotion. e xe” -s -n 250 -b 200
The last argument is the backoff pa r ameter.
Changing the “Backoff” Parameter
The -n x bu ff ers are used to store incoming image data before being wri tt en to the target drive. This is
done because the target drive will not read at a consistent rate, especially as it deals with file s ystem
overheads and other housekeeping tasks. The drive will tend to get a little behind, then c atching up.
If the drive gets too far behind, the system may run out of bu ff ers before it gets caught up. Fas M otion
can tell the camera to stop temporarily while the system catches up, but it takes a while for that
message to get to the camera, and there may be quite a few images already in the pipeline when the
message is sent. FasMotion needs t o send the message well before it runs out of bu ff ers or it will start
missing packets.
The default backoff is 1/2 the bu
ff er value. If you have designated 200 bu ff ers, the default backoff
will be 100, meaning that when there are fewer than 100 bu ff ers remaining, the system tells the
camera to stop sending data for a while.
On a very fast system that has the packet delay set very low, the system will use its bu
ff ers very
quickly, so it may be good to set the backoff t o a value higher than the default. An example of the is
the system used for “Table 10-2: Table Stats.txt Moderate_Performance System” on page 105. This
system has 8GB of memory, is a dedicated system for camera downloads, and is operating with a
v ery small packet delay. Notice th a t for some of the saves at 512 x 512, the Min (minimum bu ff ers)
goes quite low--one goes all the way down to 18. Had the all of the bu ff ers been exhausted, the
system would have missed frames and lost a lot of time with r etries.
One way to avoid this would be to change the packet delay to a higher number. Another way to avoid
this would be to set the bu ff ers up higher (there is plenty of RAM available) and set the backoff higher
as well, so the system has a little mo r e time t o recover when it gets a little behind
“...\FasMotion\ F asMotion. e xe” -s -n 300 -b 200