Re: [PATCH v7 8/8] perf record: Unmap overwrite evlist when event terminate

[Wangnan (F)]

On 2016/6/17 4:59, Arnaldo Carvalho de Melo wrote:
> Em Wed, Jun 15, 2016 at 02:23:35AM +0000, Wang Nan escreveu:
> > When see POLLERR or POLLHUP, unmap ring buffer from both the main
> > evlist and overwrite evlist.
> When you use an auxiliary evlist this makes evlist->parent be different
> than evlist, right? So can't we just hide this from tools and do it all
> in perf_evlist__filter_pollfd?

So we need to find all children from parent. Currently we can only track
parent from children. This is not enough. Although currently we can pass
rec->overwrite_evlist to the filter so perf_evlist__filter_pollfd knows
it should release mmaps from both evlists, if in future we have more than
one aux_evlists it doesn't work.

Thank you.


> This way we will not need to expose perf_evlist__mmap_put(), etc.
>
> I haven't tried to _actually_ do this, just asking from browsing the
> patchkit and with the goal of hiding the internals of this thing inside
> evlist.c as much as possible.
>
> - Arnaldo
>   
> > Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> > Cc: He Kuang <hekuang@xxxxxxxxxx>
> > Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> > Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> > Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> > Cc: Zefan Li <lizefan@xxxxxxxxxx>
> > Cc: pi3orama@xxxxxxx
> > ---
> >   tools/perf/builtin-record.c | 30 +++++++++++++++++++++---------
> >   tools/perf/util/evlist.c    |  3 +--
> >   tools/perf/util/evlist.h    |  2 +-
> >   3 files changed, 23 insertions(+), 12 deletions(-)
> >
> > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > index b9094f0..ca6376c 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -914,6 +914,26 @@ out:
> >   	return err;
> >   }
> >   
> > +static void record__munmap_filtered(struct fdarray *fda, int fd, void *arg)
> > +{
> > +	struct record *rec = (struct record *)arg;
> > +
> > +	perf_evlist__mmap_put(rec->evlist, fda->priv[fd].idx);
> > +	if (rec->overwrite_evlist)
> > +		perf_evlist__mmap_put(rec->overwrite_evlist, fda->priv[fd].idx);
> > +}
> > +
> > +static int record__filter_pollfd(struct record *rec)
> > +{
> > +	/*
> > +	 * Although we may have auxiliray evlist, there is
> > +	 * only one pollfd, so we don't need to filter pollfd
> > +	 * for auxiliray evlist.
> > +	 */
> > +	return fdarray__filter(&rec->evlist->pollfd, POLLERR | POLLHUP,
> > +			       record__munmap_filtered, rec);
> > +}
> > +
> >   static int __cmd_record(struct record *rec, int argc, const char **argv)
> >   {
> >   	int err;
> > @@ -1150,15 +1170,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
> >   				err = 0;
> >   			waking++;
> >   
> > -			/*
> > -			 * Although we may have auxiliray evlist, there is
> > -			 * only one pollfd, so we don't need to filter pollfd
> > -			 * for auxiliray evlist.
> > -			 *
> > -			 * TODO: if an event is terminated (POLLERR | POLLHUP),
> > -			 * unmap mmaps for auxiliray evlist too.
> > -			 */
> > -			if (perf_evlist__filter_pollfd(rec->evlist, POLLERR | POLLHUP) == 0)
> > +			if (record__filter_pollfd(rec) == 0)
> >   				draining = true;
> >   		}
> >   
> > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> > index e8fcb22..d43ee81 100644
> > --- a/tools/perf/util/evlist.c
> > +++ b/tools/perf/util/evlist.c
> > @@ -27,7 +27,6 @@
> >   #include <linux/log2.h>
> >   #include <linux/err.h>
> >   
> > -static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx);
> >   static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx);
> >   
> >   #define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
> > @@ -863,7 +862,7 @@ static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx)
> >   	atomic_inc(&evlist->mmap[idx].refcnt);
> >   }
> >   
> > -static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
> > +void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
> >   {
> >   	struct perf_mmap *md = &evlist->mmap[idx];
> >   
> > diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> > index 41e65ac..ba5e006 100644
> > --- a/tools/perf/util/evlist.h
> > +++ b/tools/perf/util/evlist.h
> > @@ -141,7 +141,7 @@ union perf_event *perf_evlist__mmap_read_backward(struct perf_evlist *evlist,
> >   void perf_evlist__mmap_read_catchup(struct perf_evlist *evlist, int idx);
> >   
> >   void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx);
> > -
> > +void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx);
> >   int perf_evlist__pause(struct perf_evlist *evlist);
> >   int perf_evlist__resume(struct perf_evlist *evlist);
> >   int perf_evlist__open(struct perf_evlist *evlist);
> > --
> > 1.8.3.4