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Date: Wed, 3 Jun 2020 14:38:27 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Alexey Budankov <alexey.budankov@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Andi Kleen <ak@...ux.intel.com>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 01/13] tools/libperf: introduce notion of static polled
file descriptors
On 1/06/20 11:05 pm, Alexey Budankov wrote:
>
> Implement adding of file descriptors by fdarray__add_stat() to
> fix-sized (currently 1) stat_entries array located at struct fdarray.
> Append added file descriptors to the array used by poll() syscall
> during fdarray__poll() call. Copy poll() result of the added
> descriptors from the array back to the storage for separate analysis.
Why not instead call evlist__add_pollfd() before other fds are added, so
the fda->entries[] position is always fixed. Then this patch is not needed.
>
> Signed-off-by: Alexey Budankov <alexey.budankov@...ux.intel.com>
> ---
> tools/lib/api/fd/array.c | 42 +++++++++++++++++++++++-
> tools/lib/api/fd/array.h | 7 ++++
> tools/lib/perf/evlist.c | 11 +++++++
> tools/lib/perf/include/internal/evlist.h | 2 ++
> 4 files changed, 61 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/api/fd/array.c b/tools/lib/api/fd/array.c
> index 58d44d5eee31..b0027f2169c7 100644
> --- a/tools/lib/api/fd/array.c
> +++ b/tools/lib/api/fd/array.c
> @@ -11,10 +11,16 @@
>
> void fdarray__init(struct fdarray *fda, int nr_autogrow)
> {
> + int i;
> +
> fda->entries = NULL;
> fda->priv = NULL;
> fda->nr = fda->nr_alloc = 0;
> fda->nr_autogrow = nr_autogrow;
> +
> + fda->nr_stat = 0;
> + for (i = 0; i < FDARRAY__STAT_ENTRIES_MAX; i++)
> + fda->stat_entries[i].fd = -1;
> }
>
> int fdarray__grow(struct fdarray *fda, int nr)
> @@ -83,6 +89,20 @@ int fdarray__add(struct fdarray *fda, int fd, short revents)
> return pos;
> }
>
> +int fdarray__add_stat(struct fdarray *fda, int fd, short revents)
> +{
> + int pos = fda->nr_stat;
> +
> + if (pos >= FDARRAY__STAT_ENTRIES_MAX)
> + return -1;
> +
> + fda->stat_entries[pos].fd = fd;
> + fda->stat_entries[pos].events = revents;
> + fda->nr_stat++;
> +
> + return pos;
> +}
> +
> int fdarray__filter(struct fdarray *fda, short revents,
> void (*entry_destructor)(struct fdarray *fda, int fd, void *arg),
> void *arg)
> @@ -113,7 +133,27 @@ int fdarray__filter(struct fdarray *fda, short revents,
>
> int fdarray__poll(struct fdarray *fda, int timeout)
> {
> - return poll(fda->entries, fda->nr, timeout);
> + int nr, i, pos, res;
> +
> + nr = fda->nr;
> +
> + for (i = 0; i < fda->nr_stat; i++) {
> + if (fda->stat_entries[i].fd != -1) {
> + pos = fdarray__add(fda, fda->stat_entries[i].fd,
> + fda->stat_entries[i].events);
> + if (pos >= 0)
> + fda->priv[pos].idx = i;
> + }
> + }
> +
> + res = poll(fda->entries, fda->nr, timeout);
> +
> + for (i = nr; i < fda->nr; i++)
> + fda->stat_entries[fda->priv[i].idx] = fda->entries[i];
> +
> + fda->nr = nr;
> +
> + return res;
> }
>
> int fdarray__fprintf(struct fdarray *fda, FILE *fp)
> diff --git a/tools/lib/api/fd/array.h b/tools/lib/api/fd/array.h
> index b39557d1a88f..9bca72e80b09 100644
> --- a/tools/lib/api/fd/array.h
> +++ b/tools/lib/api/fd/array.h
> @@ -3,6 +3,7 @@
> #define __API_FD_ARRAY__
>
> #include <stdio.h>
> +#include <poll.h>
>
> struct pollfd;
>
> @@ -16,6 +17,9 @@ struct pollfd;
> * I.e. using 'fda->priv[N].idx = * value' where N < fda->nr is ok,
> * but doing 'fda->priv = malloc(M)' is not allowed.
> */
> +
> +#define FDARRAY__STAT_ENTRIES_MAX 1
> +
> struct fdarray {
> int nr;
> int nr_alloc;
> @@ -25,6 +29,8 @@ struct fdarray {
> int idx;
> void *ptr;
> } *priv;
> + int nr_stat;
> + struct pollfd stat_entries[FDARRAY__STAT_ENTRIES_MAX];
> };
>
> void fdarray__init(struct fdarray *fda, int nr_autogrow);
> @@ -34,6 +40,7 @@ struct fdarray *fdarray__new(int nr_alloc, int nr_autogrow);
> void fdarray__delete(struct fdarray *fda);
>
> int fdarray__add(struct fdarray *fda, int fd, short revents);
> +int fdarray__add_stat(struct fdarray *fda, int fd, short revents);
> int fdarray__poll(struct fdarray *fda, int timeout);
> int fdarray__filter(struct fdarray *fda, short revents,
> void (*entry_destructor)(struct fdarray *fda, int fd, void *arg),
> diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
> index 6a875a0f01bb..e68e4c08e7c2 100644
> --- a/tools/lib/perf/evlist.c
> +++ b/tools/lib/perf/evlist.c
> @@ -317,6 +317,17 @@ int perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd,
> return pos;
> }
>
> +int perf_evlist__add_pollfd_stat(struct perf_evlist *evlist, int fd,
> + short revent)
> +{
> + int pos = fdarray__add_stat(&evlist->pollfd, fd, revent | POLLERR | POLLHUP);
> +
> + if (pos >= 0)
> + fcntl(fd, F_SETFL, O_NONBLOCK);
> +
> + return pos;
> +}
> +
> static void perf_evlist__munmap_filtered(struct fdarray *fda, int fd,
> void *arg __maybe_unused)
> {
> diff --git a/tools/lib/perf/include/internal/evlist.h b/tools/lib/perf/include/internal/evlist.h
> index 74dc8c3f0b66..2b3b4518c05e 100644
> --- a/tools/lib/perf/include/internal/evlist.h
> +++ b/tools/lib/perf/include/internal/evlist.h
> @@ -46,6 +46,8 @@ struct perf_evlist_mmap_ops {
> int perf_evlist__alloc_pollfd(struct perf_evlist *evlist);
> int perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd,
> void *ptr, short revent);
> +int perf_evlist__add_pollfd_stat(struct perf_evlist *evlist, int fd,
> + short revent);
>
> int perf_evlist__mmap_ops(struct perf_evlist *evlist,
> struct perf_evlist_mmap_ops *ops,
>
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