Re: arm/arm64 perf build issue with mainline

From: David Ahern
Date: Thu Apr 23 2015 - 10:16:34 EST


On 4/23/15 8:04 AM, Will Deacon wrote:
From 28740111e81aa9247bf48e3125dc43cc31d94e6f Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@xxxxxxx>
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@xxxxxxx>
---
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


Certainly a more robust way of doing it but I am concerned this might end up breaking others. For Fedora at least getconf is in the glibc-common package and there are users that do not build with glibc. It is not clear if the build system for those environments will have getconf.
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