AR# 18888

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9.1i PAR - How much memory is available to PAR under Linux?

Description

I am running PAR on a large design using a Linux machine with 4 Gb of memory. PAR runs out of memory even though only 2.3 Gb of memory were used.

What are the limiting factors for memory utilization on a Linux machine?

"(FATAL_ERROR:Portability:3 - This Xilinx application has run out of memory)."

Solution

Available application memory for a system with a standard kernel is calculated as:

(lesser of 4 Gb or your memory size) - 1 Gb (reserved for the kernel) - "overhead"

where the "overhead" is the size of the executable and linked libraries, typically around 700 Mb for PAR.

A 4 Gb Linux machine will have ~2.3 Gb available. This memory limitation can be increased by recompiling the kernel to reserve less than 1 Gb of memory; for example, if the kernel reserves 500 Mb, then PAR will have ~2.8 Gb of memory available.

See (Xilinx Answer 17445) for more details regarding kernel modifications.

AR# 18888
Date 12/15/2012
Status Archive
Type General Article
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