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SubjectRe: arm/arm64 perf build issue with mainline
On Thu, Apr 23, 2015 at 12:29:16PM +0100, 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?

Scratch that, how about using sysconf instead? Patch below...

Will

--->8

From 28740111e81aa9247bf48e3125dc43cc31d94e6f Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Thu, 23 Apr 2015 15:00:16 +0100
Subject: [PATCH] tools: perf: use getconf to determine number of online CPUs

Parsing /proc/cpuinfo is a fiddly, arch-dependent business anda recent
change to get it working for Sparc broke arm and arm64 platforms.

Instead, use sysconf to determine the number of online CPUs and avoid
parsing /proc/cpuinfo entirely.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
tools/perf/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index c699dc35eef9..c26cb04ce6bd 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -24,7 +24,7 @@ unexport MAKEFLAGS
# (To override it, run 'make JOBS=1' and similar.)
#
ifeq ($(JOBS),)
- JOBS := $(shell egrep -c '^processor|^CPU' /proc/cpuinfo 2>/dev/null)
+ JOBS := $(shell getconf _NPROCESSORS_ONLN 2>/dev/null)
ifeq ($(JOBS),0)
JOBS := 1
endif
--
2.1.4


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