User Manual

Chapter 4: Configuring Your Pro Tools System 19
Host Processors
The Host Processors setting lets you manage
multi-processor support for RTAS (Real-Time
AudioSuite) plug-in processing.
Used in combination with the CPU Usage Limit
setting, the Host Processors setting lets you con-
trol the way RTAS and other host-based process-
ing tasks are carried out by the system.
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 Host Processors to RTAS and set a
low CPU Usage Limit settings to leave more host
processing resources available for automation
accuracy, screen response, and video.
• 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 RTAS Processors:
1 Choose Setup > Playback Engine.
2 From the Host Processing pop-up menu, select
the number of available processors you want to
allocate. The number of processors available var-
ies depending on your computer:
• Select 1Processor to limit processing to
one CPU in the system.
• Choose 2 Processors to enable load balanc-
ing across two available processors.
• On systems running four or more proces-
sors, choose the number of processors for
processing.
3 Click OK.
System Usage Window and Processing
The System Usage window (Windows > System
Usage) displays the combined amount of pro-
cessing occurring on all enabled processors with
a single indicator, regardless of how many pro-
cessors are available in the system. If the System
Usage Window shows that you are at the limit of
available resources, increase the number of pro-
cessors and adjust the CPU Usage Limit setting.