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authorChristophe Leroy <christophe.leroy@c-s.fr>2017-09-22 13:20:43 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-08-01 12:33:24 -0300
commit21b8732eb4479b579bda9ee38e62b2c312c2a0e5 (patch)
treeb662ac8de7d6491f61e64e5f67daeab1bb0d18b1 /tools
parent739e2edc848af30fefa66d6c422c00ca9a701c06 (diff)
downloadlinux-21b8732eb4479b579bda9ee38e62b2c312c2a0e5.tar.bz2
perf tools: Allow overriding MAX_NR_CPUS at compile time
After update of kernel, the perf tool doesn't run anymore on my 32MB RAM powerpc board, but still runs on a 128MB RAM board: ~# strace perf execve("/usr/sbin/perf", ["perf"], [/* 12 vars */]) = -1 ENOMEM (Cannot allocate memory) --- SIGSEGV {si_signo=SIGSEGV, si_code=SI_KERNEL, si_addr=0} --- +++ killed by SIGSEGV +++ Segmentation fault objdump -x shows that .bss section has a huge size of 24Mbytes: 27 .bss 016baca8 101cebb8 101cebb8 001cd988 2**3 With especially the following objects having quite big size: 10205f80 l O .bss 00140000 runtime_cycles_stats 10345f80 l O .bss 00140000 runtime_stalled_cycles_front_stats 10485f80 l O .bss 00140000 runtime_stalled_cycles_back_stats 105c5f80 l O .bss 00140000 runtime_branches_stats 10705f80 l O .bss 00140000 runtime_cacherefs_stats 10845f80 l O .bss 00140000 runtime_l1_dcache_stats 10985f80 l O .bss 00140000 runtime_l1_icache_stats 10ac5f80 l O .bss 00140000 runtime_ll_cache_stats 10c05f80 l O .bss 00140000 runtime_itlb_cache_stats 10d45f80 l O .bss 00140000 runtime_dtlb_cache_stats 10e85f80 l O .bss 00140000 runtime_cycles_in_tx_stats 10fc5f80 l O .bss 00140000 runtime_transaction_stats 11105f80 l O .bss 00140000 runtime_elision_stats 11245f80 l O .bss 00140000 runtime_topdown_total_slots 11385f80 l O .bss 00140000 runtime_topdown_slots_retired 114c5f80 l O .bss 00140000 runtime_topdown_slots_issued 11605f80 l O .bss 00140000 runtime_topdown_fetch_bubbles 11745f80 l O .bss 00140000 runtime_topdown_recovery_bubbles This is due to commit 4d255766d28b1 ("perf: Bump max number of cpus to 1024"), because many tables are sized with MAX_NR_CPUS This patch gives the opportunity to redefine MAX_NR_CPUS via $ make EXTRA_CFLAGS=-DMAX_NR_CPUS=1 Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20170922112043.8349468C57@po15668-vm-win7.idsi0.si.c-s.fr Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/perf.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index d215714f48df..21bf7f5a3cf5 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -25,7 +25,9 @@ static inline unsigned long long rdclock(void)
return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
}
+#ifndef MAX_NR_CPUS
#define MAX_NR_CPUS 1024
+#endif
extern const char *input_name;
extern bool perf_host, perf_guest;