User Manual

Chapter 6: System Setup 63
For example:
• For sessions with large numbers of RTAS plug-
ins, you can allocate 2 or more processors to
RTAS processing and set a high CPU Usage
Limit.
• For sessions with few RTAS plug-ins, you can
allocate fewer processors to RTAS processing
and set a low CPU Usage Limit to leave more
CPU resources available for automation accu-
racy, screen response, and video.
• Increase these settings to accommodate TDM
to RTAS plug-in conversion. Conversely, de-
crease these settings if you are only using
TDM plug-ins or are converting RTAS plug-ins
to TDM. TDM/RTAS conversion can be desir-
able during recording, depending on latency,
voicing needs, and record-monitoring capa-
bilities of the specific TDM and RTAS plug-ins.
• Depending on the importance of video and
overall screen response, and on the density of
automation being employed, try different
combinations of Host Processors and CPU Us-
age Limit settings to achieve the best results.
For example, to improve screen response in a
medium-sized session using a moderate num-
ber of RTAS plug-ins, try reducing the number
of RTAS plug-ins, but keep the CPU Usage Limit
set to the maximum (up to 99% on a single
processor system).
To set the number of Host Processors:
1 Choose Setup > Playback Engine.
2 From the Host Processors pop-up menu, select
the number of available processors you want to
allocate. The number of processors available var-
ies depending on how many processors are
available on your computer:
• Select 1Processor to limit host processing
for Pro Tools to one CPU in the system.
• Choose 2 Processors to enable load balanc-
ing across two available processors for
Pro Tools host processing tasks.
• On systems running four or more proces-
sors, choose the number of processors for
Pro Tools host processing tasks.
3 Click OK.
System Usage Window and Host Processing
The System Usage window (Windows > System
Usage) displays the combined amount of host
processing occurring on all enabled processors
with a single indicator, regardless of how many
processors are available in the system. If the Sys-
tem Usage Window shows that you are at the
limit of available resources, increase the number
of Host Processors and adjust the CPU Usage
Limit setting. (For more information, see “Sys-
tem Usage” on page 80.)
CPU Usage Limit
The CPU Usage Limit setting in the Playback En-
gine controls the percentage of CPU resources
allocated to Pro Tools host processing tasks.
Used in combination with the Host Processors
setting, the CPU Usage Limit setting lets you con-
trol the way Pro Tools tasks are carried out by
the system.
•Lower CPU Usage Limit settings limit the effect
of Pro Tools processing on other CPU-inten-
sive tasks, such as screen redraws, and are use-
ful when you are experiencing slow system
response, or when running other applications
at the same time as Pro Tools.
•Higher CPU Usage Limit settings allocate more
processing power to Pro Tools, and are useful
for playing back large sessions or using more
RTAS plug-ins.