> On 06-May-2022, at 3:03 PM, Athira Rajeev <atraj...@linux.vnet.ibm.com> wrote:
>
>
>
>> On 05-May-2022, at 10:54 PM, Arnaldo Carvalho de Melo <a...@kernel.org>
>> wrote:
>>
>> Em Thu, May 05, 2022 at 03:09:59PM +0530, Athira Rajeev escreveu:
>>> /proc/cpuinfo provides information about type of processor, number
>>> of CPU's etc. Reading /proc/cpuinfo file outputs useful information
>>> by field name like cpu, platform, model (depending on architecture)
>>> and its value separated by colon.
>>>
>>> Add new utility function "cpuinfo_field" in "util/header.c" which
>>> accepts field name as input string to search in /proc/cpuinfo content.
>>> This returns the first matching value as resulting string. Example,
>>> calling the function "cpuinfo_field(platform)" in powerpc returns
>>> the platform value. This can be used to fetch processor information
>>> from "cpuinfo" by other utilities/testcases.
>>>
>>> Signed-off-by: Athira Rajeev <atraj...@linux.vnet.ibm.com>
>>> ---
>>> tools/perf/util/header.c | 53 ++++++++++++++++++++++++++++++++++++++++
>>> tools/perf/util/header.h | 1 +
>>> 2 files changed, 54 insertions(+)
>>>
>>> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
>>> index a27132e5a5ef..f08857f96606 100644
>>> --- a/tools/perf/util/header.c
>>> +++ b/tools/perf/util/header.c
>>> @@ -983,6 +983,59 @@ static int write_dir_format(struct feat_fd *ff,
>>> return do_write(ff, &data->dir.version, sizeof(data->dir.version));
>>> }
>>>
>>> +/*
>>> + * Return entry from /proc/cpuinfo
>>> + * indicated by "search" parameter.
>>> + */
>>> +char *cpuinfo_field(const char *search)
>>> +{
>>> + FILE *file;
>>> + char *buf = NULL;
>>> + char *copy_buf = NULL, *p;
>>> + size_t len = 0;
>>> +
>>> + if (!search)
>>> + return NULL;
>>> +
>>> + file = fopen("/proc/cpuinfo", "r");
>>> + if (!file)
>>> + return NULL;
>>> +
>>> + while (getline(&buf, &len, file) > 0) {
>>> + if (!strncmp(buf, search, strlen(search)))
>>
>> Can you save the search string lenght in a variable and use it instead
>> of calling strlen() for the same buffer for each line in /proc/cpuinfo?
>
>
> Hi Arnaldo, Michael
>
> Thanks for review comments. Based on suggestion from Michael, I am reworking
> on patch 2 to SKIP the test
> if physical_id is set to -1 irrespective of value from cpuinfo.
>
> In this patch, I had written "cpuinfo_field " function as generic function
> for retrieving any entry from /proc/cpuinfo.
> But it won't be used in patch 2 now. Do you think this function is useful to
> keep ? Otherwise, I will drop patch 1
Hi,
Requesting for suggestions on this change
Thanks
Athira
>
> Thanks
> Athira Rajeev
>
>>
>>> + break;
>>> + }
>>> +
>>> + if (feof(file))
>>> + goto done;
>>> +
>>> + /*
>>> + * Trim the new line and separate
>>> + * value for search field from ":"
>>> + * in cpuinfo line output.
>>> + * Example output line:
>>> + * platform : <value>
>>> + */
>>> + copy_buf = buf;
>>> + p = strchr(copy_buf, ':');
>>
>> So you assume that this will always be there, right? Shouldn't we not
>> assume that and check if p is NULL and bail out instead?
>>
>>> +
>>> + /* Go to string after ":" */
>>> + copy_buf = p + 1;
>>> + p = strchr(copy_buf, '\n');
>>
>> Ditto.
>>
>>> + if (p)
>>> + *p = '\0';
>>> +
>>> + /* Copy the filtered string after removing space to buf */
>>> + strcpy(buf, strim(copy_buf));
>>> +
>>> + fclose(file);
>>> + return buf;
>>> +
>>> +done:
>>
>> Please rename this goto label to "not_found", "done" isn't intention
>> revealing.
>>
>>> + free(buf);
>>> + fclose(file);
>>> + return NULL;
>>> +}
>>> /*
>>> * Check whether a CPU is online
>>> *
>>> diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
>>> index 0eb4bc29a5a4..b0f754364bd4 100644
>>> --- a/tools/perf/util/header.h
>>> +++ b/tools/perf/util/header.h
>>> @@ -166,4 +166,5 @@ int get_cpuid(char *buffer, size_t sz);
>>>
>>> char *get_cpuid_str(struct perf_pmu *pmu __maybe_unused);
>>> int strcmp_cpuid_str(const char *s1, const char *s2);
>>> +char *cpuinfo_field(const char *search);
>>> #endif /* __PERF_HEADER_H */
>>> --
>>> 2.35.1
>>
>> --
>>
>> - Arnaldo
