Re: [PATCH 7/7] perf tools: Refine perf_mmap__read_init

[Liang, Kan]

On 3/5/2018 5:25 PM, Jiri Olsa wrote:
> On Mon, Mar 05, 2018 at 02:10:59PM -0500, kan.liang@xxxxxxxxxxxxxxx wrote:
>
> SNIP
>
> > diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> > index e3921ed..403c5e6 100644
> > --- a/tools/perf/util/mmap.c
> > +++ b/tools/perf/util/mmap.c
> > @@ -235,16 +235,13 @@ static int overwrite_rb_find_range(void *buf, int mask, u64 head, u64 *start, u6
> >   /*
> >    * Report the start and end of the available data in ringbuffer
> >    */
> > -int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
> > -			 u64 *startp, u64 *endp)
> > +int perf_mmap__read_init(struct perf_mmap *md, bool overwrite)
> >   {
> >   	u64 head = perf_mmap__read_head(md);
> >   	u64 old = md->prev;
> >   	unsigned char *data = md->base + page_size;
> >   	unsigned long size;
> >   
> > -	*startp = overwrite ? head : old;
> > -	*endp = overwrite ? old : head;
> >   	md->overwrite = overwrite;
>
> hum, can't we set 'overwrite' at the moment we create struct perf_mmap?
>
> it's not changing during the mmap's lifetime.. maybe we could do it in
> perf_evlist__alloc_mmap function

Yes, we know that the __alloc_mmap() is for mmap or overwrite_mmap.
I think we can set the 'overwrite' there.
I will do the change in V2.

Thanks,
Kan

> really nice cleanup!
>
> thanks,
> jirka