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| Started by | Christophe Leroy <christophe.leroy@c-s.fr> |
|---|---|
| First post | 2017-09-22 13:30 +0200 |
| Last post | 2017-09-22 16:10 +0200 |
| Articles | 2 — 2 participants |
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[PATCH] perf tools: allow overriding MAX_NR_CPUS at compile time Christophe Leroy <christophe.leroy@c-s.fr> - 2017-09-22 13:30 +0200
Re: [PATCH] perf tools: allow overriding MAX_NR_CPUS at compile time Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-22 16:10 +0200
| From | Christophe Leroy <christophe.leroy@c-s.fr> |
|---|---|
| Date | 2017-09-22 13:30 +0200 |
| Subject | [PATCH] perf tools: allow overriding MAX_NR_CPUS at compile time |
| Message-ID | <usujE-5v6-15@gated-at.bofh.it> |
After update of kernel, 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>
---
tools/perf/perf.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index dc442ba21bf6..a9db563da0a9 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -23,7 +23,9 @@ 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;
--
2.13.3
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| From | Arnaldo Carvalho de Melo <acme@kernel.org> |
|---|---|
| Date | 2017-09-22 16:10 +0200 |
| Message-ID | <uswOu-72F-11@gated-at.bofh.it> |
| In reply to | #1737424 |
Em Fri, Sep 22, 2017 at 01:20:43PM +0200, Christophe Leroy escreveu:
> After update of kernel, 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
I'll probably apply this, but the right thing would be to get rid of
MAX_NR_CPUS completely and instead allocate that using sysconf:
[root@jouet ~]# perf trace -e open,getdents getconf _NPROCESSORS_CONF
4
0.014 ( 0.011 ms): getconf/2452 open(filename: /etc/ld.so.cache, flags: CLOEXEC ) = 3
0.045 ( 0.008 ms): getconf/2452 open(filename: /lib64/libc.so.6, flags: CLOEXEC ) = 3
0.264 ( 0.012 ms): getconf/2452 open(filename: /usr/lib/locale/locale-archive, flags: CLOEXEC ) = 3
0.315 ( 0.028 ms): getconf/2452 open(filename: /sys/devices/system/cpu, flags: CLOEXEC|DIRECTORY|NONBLOCK) = 3
0.349 ( 0.013 ms): getconf/2452 getdents(fd: 3</sys/devices/system/cpu>, dirent: 0x944030, count: 32768) = 624
0.365 ( 0.001 ms): getconf/2452 getdents(fd: 3</sys/devices/system/cpu>, dirent: 0x944030, count: 32768) = 0
[root@jouet ~]#
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> tools/perf/perf.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/tools/perf/perf.h b/tools/perf/perf.h
> index dc442ba21bf6..a9db563da0a9 100644
> --- a/tools/perf/perf.h
> +++ b/tools/perf/perf.h
> @@ -23,7 +23,9 @@ 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;
> --
> 2.13.3
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