Re: [PATCH 02/26] perf: Introduce mmap3 version of mmap event

[Jiri Olsa]

On Sun, Sep 13, 2020 at 11:20:31PM -0700, Song Liu wrote:
> On Sun, Sep 13, 2020 at 10:40 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
> >
> > On Mon, Sep 14, 2020 at 6:03 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> > >
> > > Add new version of mmap event. The MMAP3 record is an
> > > augmented version of MMAP2, it adds build id value to
> > > identify the exact binary object behind memory map:
> > >
> > >   struct {
> > >     struct perf_event_header header;
> > >
> > >     u32                      pid, tid;
> > >     u64                      addr;
> > >     u64                      len;
> > >     u64                      pgoff;
> > >     u32                      maj;
> > >     u32                      min;
> > >     u64                      ino;
> > >     u64                      ino_generation;
> > >     u32                      prot, flags;
> > >     u32                      reserved;
> 
> I guess we need reserved _after_ buildid, no?

it's there to align the size to 8 bytes,
so the sample_id is in proper place

but yes, perhaps after buildid would make more sense

> 
> > >     u8                       buildid[20];
> >
> > Do we need maj, min, ino, ino_generation for mmap3 event?
> > I think they are to compare binaries, then we can do it with
> > build-id (and I think it'd be better)..
> 
> +1 we shouldn't need maj, min, etc.

right, and as peter already wrote buildid could fit
in that space.. yay :)

thanks,
jirka

> 
> Thanks,
> Song
> 
> [...]
>