On 05.06.2020 19:15, Alexey Budankov wrote:
>
> On 05.06.2020 14:38, Jiri Olsa wrote:
>> On Fri, Jun 05, 2020 at 12:50:54PM +0200, Jiri Olsa wrote:
>>> On Wed, Jun 03, 2020 at 06:52:59PM +0300, 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 analysis.
>>>>
>>>> Signed-off-by: Alexey Budankov <alexey.budan...@linux.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);
>>>
>>> so every call to fdarray__poll will add whatever is
>>> in stat_entries to entries? how is it removed?
>>>
>>> I think you should either follow what Adrian said
>>> and put 'static' descriptors early and check for
>>> filter number to match it as an 'quick fix'
>>>
>>> or we should fix it for real and make it generic
>>>
>>> so currently the interface is like this:
>>>
>>> pos1 = fdarray__add(a, fd1 ... );
>>> pos2 = fdarray__add(a, fd2 ... );
>>> pos3 = fdarray__add(a, fd2 ... );
>>>
>>> fdarray__poll(a);
>>>
>>> num = fdarray__filter(a, revents, destructor, arg);
>>>
>>> when fdarray__filter removes some of the fds the 'pos1,pos2,pos3'
>>> indexes are not relevant anymore
>
> and that is why the return value of fdarray__add() should be converted
> to bool (added/not added). Currently the return value is used as bool
> only allover the calling code.
>
> fdarray__add_fixed() brings the notion of fd with fixed pos which is
> valid after fdarray__add_fixed() call so the pos could be used to access
> pos fd poll status after poll() call.
>
> pos = fdarray__add_fixed(array, fd);
> fdarray_poll(array);
> revents = fdarray_fixed_revents(array, pos);
> fdarray__del(array, pos);
So how is it about just adding _revents() and _del() for fixed fds with
correction of retval to bool for fdarray__add()?
~Alexey
