linux-kernel - Re: [PATCH] perf: change samples type to unsigned long long

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Date:	Fri, 02 Oct 2015 14:25:53 -0700
From:	"Shi, Yang" <yang.shi@...aro.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
CC:	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH] perf: change samples type to unsigned long long

On 10/2/2015 12:10 PM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Oct 02, 2015 at 04:08:38PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Tue, Sep 29, 2015 at 02:49:43PM -0700, Yang Shi escreveu:
>>> When run "perf record -e", the number of samples showed up is wrong on some
>>> 32 bit systems, i.e. powerpc and arm.
>>>
>>> For example, run the below commands on 32 bit powerpc:
>>>
>>> perf probe -x /lib/libc.so.6 malloc
>>> perf record -e probe_libc:malloc -a ls
>>> perf.data
>>> [ perf record: Woken up 1 times to write data ]
>>> [ perf record: Captured and wrote 0.036 MB perf.data (13829241621624967218 samples) ]
>>>
>>> Actually, "perf script" just shows 21 samples. The number of samples is also
>>> absurd since samples is long type, but it is printed as PRIu64.
>>>
>>> Build test is run on x86-64, x86, aarch64, arm, mips, ppc and ppc64.
>>
>> Sure?
>>
>>    AR       /tmp/build/perf/libperf.a
>> builtin-record.c: In function ‘__cmd_record’:
>> builtin-record.c:689:12: error: comparison between signed and unsigned
>> integer expressions [-Werror=sign-compare]
>
> You missed something important, I am fixing this and applying your
> patch:

Thanks a lot. Yes, it was wrong, however, my compiler just throws a 
warning instead of an error. And, the warning was hidden by my OE build 
environment.

Regards,
Yang

>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 974065f8ce80..24ace2f318c1 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -667,7 +667,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
>
>   	auxtrace_snapshot_enabled = 1;
>   	for (;;) {
> -		int hits = rec->samples;
> +		unsigned long long hits = rec->samples;
>
>   		if (record__mmap_read_all(rec) < 0) {
>   			auxtrace_snapshot_enabled = 0;
>

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