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

[Sapkal, Swapnil]

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@xxxxxxx>
> >
> > 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@xxxxxxx>
> > Co-developed-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
> > Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
> > ---
>
> [...]
>
> > +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