Re: [PATCH 1/2] tools/perf: Add utility function to read /proc/cpuinfo for any field
> On 04-May-2022, at 7:16 PM, kajoljain wrote:
>
>
>
> On 4/28/22 20:38, Athira Rajeev wrote:
>> /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
>> ---
>> tools/perf/util/header.c | 54
>> tools/perf/util/header.h | 1 +
>> 2 files changed, 55 insertions(+)
>>
>> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
>> index a27132e5a5ef..0c8dfd0c1e78 100644
>> --- a/tools/perf/util/header.c
>> +++ b/tools/perf/util/header.c
>> @@ -983,6 +983,60 @@ static int write_dir_format(struct feat_fd *ff,
>> return do_write(ff, >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;
>> +int ret = -1;
>> +
>> +if (!search)
>> +return NULL;
>> +
>> +file = fopen("/proc/cpuinfo", "r");
>> +if (!file)
>> +return NULL;
>> +
>> +while (getline(, , file) > 0) {
>> +ret = strncmp(buf, search, strlen(search));
>> +if (!ret)
>> +break;
> Hi Athira,
> Do we need ret variable. Since we will come out of the loop only when
> we reach EOF.
>
>> +}
>> +
>> +if (ret)
>> +goto done;
>> +
>> +/*
>> + * Trim the new line and separate
>> + * value for search field from ":"
>> + * in cpuinfo line output.
>> + * Example output line:
>> + * platform :
>> + */
>> +copy_buf = buf;
>> +p = strchr(copy_buf, ':');
>> +if (p && *(p+1) == ' ' && *(p+2))
>
>
> Can you try using strim instead to remove whitespaces. This function
> will remove leading and trailing whitespaces from the string.
Hi Kajol,
Thanks for review comments.
I will send V2 addressing these changes
Athira
>
>> +copy_buf = p + 2;
>> +p = strchr(copy_buf, '\n');
>
> do we need to replace `\n` here ?
>
>
>> +if (p)
>> +*p = '\0';
>> +
>> +/* Copy the filtered string to buf */
>> +strcpy(buf, copy_buf)
>
> You are initializing buf to NULL. So do we need to do fclose and return
> buf separately here? Can you move free(buf) in above condition and reuse
> `done` code.
>> +
>> +fclose(file);
>> +return buf;> +
>> +done:
>> +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 */
Re: [PATCH 1/2] tools/perf: Add utility function to read /proc/cpuinfo for any field
On 4/28/22 20:38, Athira Rajeev wrote:
> /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
> ---
> tools/perf/util/header.c | 54
> tools/perf/util/header.h | 1 +
> 2 files changed, 55 insertions(+)
>
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index a27132e5a5ef..0c8dfd0c1e78 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -983,6 +983,60 @@ static int write_dir_format(struct feat_fd *ff,
> return do_write(ff, >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;
> + int ret = -1;
> +
> + if (!search)
> + return NULL;
> +
> + file = fopen("/proc/cpuinfo", "r");
> + if (!file)
> + return NULL;
> +
> + while (getline(, , file) > 0) {
> + ret = strncmp(buf, search, strlen(search));
> + if (!ret)
> + break;
Hi Athira,
Do we need ret variable. Since we will come out of the loop only when
we reach EOF.
> + }
> +
> + if (ret)
> + goto done;
> +
> + /*
> + * Trim the new line and separate
> + * value for search field from ":"
> + * in cpuinfo line output.
> + * Example output line:
> + * platform :
> + */
> + copy_buf = buf;
> + p = strchr(copy_buf, ':');
> + if (p && *(p+1) == ' ' && *(p+2))
Can you try using strim instead to remove whitespaces. This function
will remove leading and trailing whitespaces from the string.
> + copy_buf = p + 2;
> + p = strchr(copy_buf, '\n');
do we need to replace `\n` here ?
> + if (p)
> + *p = '\0';
> +
> + /* Copy the filtered string to buf */
> + strcpy(buf, copy_buf)
You are initializing buf to NULL. So do we need to do fclose and return
buf separately here? Can you move free(buf) in above condition and reuse
`done` code.
> +
> + fclose(file);
> + return buf;> +
> +done:
> + 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 */
