Re: [PATCH] perf tools: fix incorrect header string
From: Wang Nan
Date: Wed Oct 15 2014 - 23:21:48 EST
On 2014/10/15 23:13, Arnaldo Carvalho de Melo wrote:
> Em Wed, Oct 15, 2014 at 11:28:53AM +0800, Wang Nan escreveu:
>> Commit fbe96f29 (perf tools: Make perf.data more self-descriptive)
>> read '/proc/cpuinfo' to form cpu descriptor. For ARM, it finds
>> 'Processor' field. It is correct when the patch merged, but due to
>> commit b4b8f770 (ARM: kernel: update cpuinfo to print all online CPUs
>> features), the corresponding information becomes 'model name' field.
>> This patch simply corrects it.
> It doesn't :-)
> It makes it work with kernels >= b4b8f770, and fail with older kernels.
> We need to somehow figure out where the right information is regardless
> of the kernel.
> - Arnaldo
However it is a real problem. Look at output on arm platform at the
bottom of this mail, especially "cpudesc", "total memory" and "cmdline" field.
By further debugging I found that the real problem resides in return value checking
when write header error. Please see my other patches:
I think at least one of them is required.
>> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
>> tools/perf/perf-sys.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> diff --git a/tools/perf/perf-sys.h b/tools/perf/perf-sys.h
>> index 937e432..4293970 100644
>> --- a/tools/perf/perf-sys.h
>> +++ b/tools/perf/perf-sys.h
>> @@ -113,7 +113,7 @@
>> #define mb() ((void(*)(void))0xffff0fa0)()
>> #define wmb() ((void(*)(void))0xffff0fa0)()
>> #define rmb() ((void(*)(void))0xffff0fa0)()
>> -#define CPUINFO_PROC "Processor"
>> +#define CPUINFO_PROC "model name"
>> #ifdef __aarch64__
bash-4.2# perf record ls
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.001 MB perf.data (~36 samples) ]
bash-4.2# perf report --stdio --header
The perf.data file has no samples!
# captured on: Fri Sep 12 10:09:10 2014
# hostname : arma15el
# os release : 3.17.0+
# perf version : 3.10.53
# arch : armv7l
# nrcpus online : 4
# nrcpus avail : 1
# cpudesc : (null)
# total memory : 0 kB
# cmdline :
# event : name = cycles, type = 0, config = 0x0, config1 = 0x0, config2 = 0x0, excl_usr = 0, excl_kern = 0, excl_host = 0, excl_guest = 1, precise_ip = 0
# pmu mappings: not available
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