Re: [PATCH 2/5] perf sched stats: Add record and rawdump support

["Sapkal, Swapnil" <swapnil.sapkal@amd.com>]

Hi James,

Thanks for the review.

On 9/17/2024 4:05 PM, James Clark wrote:
> 
> 
> On 16/09/2024 17:47, Ravi Bangoria wrote:
>> From: Swapnil Sapkal <swapnil.sapkal@amd.com>
>>
>> Define new, perf tool only, sample types and their layouts. Add logic
>> to parse /proc/schedstat, convert it to perf sample format and save
>> samples to perf.data file with `perf sched stats record` command. Also
>> add logic to read perf.data file, interpret schedstat samples and
>> print rawdump of samples with `perf script -D`.
>>
>> Note that, /proc/schedstat file output is standardized with version
>> number. The patch supports v15 but older or newer version can be added
>> easily.
>>
>> Signed-off-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
>> Co-developed-by: Ravi Bangoria <ravi.bangoria@amd.com>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
>> ---
> 
> [...]
> 
>> +int perf_event__synthesize_schedstat(const struct perf_tool *tool,
>> +                     perf_event__handler_t process,
>> +                     struct perf_cpu_map *user_requested_cpus)
>> +{
>> +    union perf_event *event = NULL;
>> +    size_t line_len = 0;
>> +    char *line = NULL;
>> +    char bf[BUFSIZ];
>> +    __u64 timestamp;
>> +    __u16 version;
>> +    struct io io;
>> +    int ret = -1;
>> +    int cpu = -1;
>> +    char ch;
>> +
>> +    io.fd = open("/proc/schedstat", O_RDONLY, 0);
> 
> Other parts of the tool use procfs__mountpoint() for /proc. Although it 
> can only be in one place so it doesn't actually make a difference for 
> this one. Probably worth it for consistency though.
> 
Sure, I will update this in the next version.

>> +    if (io.fd < 0) {
>> +        pr_err("Failed to open /proc/schedstat\n");
> 
> A hint about CONFIG_SCHEDSTAT would be useful here.

Sure, I will update.

--
Thanks and Regards,
Swapnil