> 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
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
