Re: arm/arm64 perf build issue with mainline

From: David Ahern
Date: Thu Apr 23 2015 - 10:29:39 EST


On 4/23/15 5:29 AM, Will Deacon wrote:
Hi all,

Commit 6428c59a97de ("perf tools: Set JOBS based on CPU or processor")
causes weird behaviour on arm/arm64 platforms because we use the "CPU"
prefix for things like:

CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd03
CPU revision : 0

in /proc/cpuinfo. Consequently, a 6 core machine ends up doing:

will@confinement-loaf:~/linux/tools/perf$ make
BUILD: Doing 'make -j36' parallel build

which is a little overwhelming. Any chance we can predicate the extra
part of the regex on $(ARCH) being sparc?


Frankly, I think the JOBS parameter needs to be removed. It's non-standard way of controlling parallelism in the build and it makes the assumption that if a system has N processors all of those can be used to build perf which is not true if you are building perf as part of bigger image builds -- like Yocto for example.

Ingo: As I recall you put this in? Opinions on removing it? Users can always add the standard '-j N' for parallelism just like they do for kernel builds.

David
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