Affinity Mask Calculator  

Flight Simulator X - FSX Steam Edition - Prepar3D (P3D V1, V2 & V3)


Important Note! Prepar3D (P3D) 2.x and 3.x Users

Please be aware that P3D V2.x & V3.x by default will use all Cores and most importantly all Threads also on CPU's that have Hyper Threading enabled. On machines with four or more cores, P3D will dedicate logical core #0 thread #0 for rendering tasks which is visually shown in the screen shot at the bottom of this page. To this end, it is suggested that the Expert Mode calculator be used to tune your P3D V2.x or V3.x Affinity Mask.

Affinity Mask Calculator - [Easy Mode] - Select CPU Core Type

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fsx.cfg or prepar3d.cfg configuration file entry to add/change

[JOBSCHEDULER]
AffinityMask=n

Affinity Mask Calculator - [Expert Mode] - Select Physical Cores - (8 Cores Supported)

    Calculate


fsx.cfg or prepar3d.cfg configuration file entry to add/change

[JOBSCHEDULER]
AffinityMask=n

What Is An Affinity Mask?

An affinity mask is a bit mask indicating which CPU Core a process should be run on by the scheduler of an operating system. Setting the affinity mask for FSX/P3D declassifies its default use of CPU cores, which can lead to better application performance.

Windows 7 - FSX SP2 - The following example uses an affinity mask value of 1364 applied to a Hexacore CPU with Hyper-threading enabled utilising cores #1 to #5, whilst running FSX SP2. Note how core #0 is almost at idle, allowing it to take care of processing other system requests and processes.

FSX FSX-SE Affinity Mask Calculator

Windows 10 - P3D v3.1 - The following example uses an affinity mask value of 4095 applied to a Hexacore CPU with Hyper-threading enabled running P3D v3.1. Note how logical core #0 thread #0 is at 100% dedicated to P3D rendering tasks. The other logical cores and threads load balance the other P3D processing requests.

P3D v1 - v2 - v3 Affinity Mask Calculator

Always backup your data before making changes to configuration files. This software has no guaranties or warranties and is used at your own risk!