On 08.06.2020 19:43, Alexey Budankov wrote:
>
> On 08.06.2020 19:07, Jiri Olsa wrote:
>> On Mon, Jun 08, 2020 at 12:54:31PM +0300, Alexey Budankov wrote:
>>>
>>> On 08.06.2020 11:43, Jiri Olsa wrote:
>>>> On Mon, Jun 08, 2020 at 11:08:56AM +0300, Alexey Budankov wrote:
>>>>>
>>>>> 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()?
>>>>
>>>> I don't like the separation for fixed and non-fixed fds,
>>>> why can't we make generic?
>>>
>>> Usage models are different but they want still to be parts of the same class
>>> for atomic poll(). The distinction is filterable vs. not filterable.
>>> The distinction should be somehow provided in API. Options are:
>>> 1. expose separate API calls like __add_nonfilterable(),
>>> __del_nonfilterable();
>>> use nonfilterable quality in __filter() and __poll() and, perhaps, other
>>> internals;
>>> 2. extend fdarray__add(, nonfilterable) with the nonfilterable quality
>>> use the type in __filter() and __poll() and, perhaps, other internals;
>>> expose less API calls in comparison with option 1
>>>
>>> Exposure of pos for filterable fds should be converted to bool since
>>> currently
>>> the returned pos can become stale and there is no way in API to check its
>>> state.
>>> So it could look like this:
>>>
>>> fdkey = fdarray__add(array, fd, events, type)
>>> type: filterable, nonfilterable, somthing else
>>> revents = fdarray__get_revents(fdkey);
>>> fdarray__del(array, fdkey);
>>
>> I think there's solution without having filterable type,
>
> and still making the atomic fdarray__poll()?
How is it about design like this?
int fdarray__poll(struct fdarray *fda, int timeout)
with additional external array of fds to simultaneously poll() on:
int fdarray__poll(struct fdarray *fda, int timeout,
int *fds, size_t fds_size)
fds would be added to array just prior poll() call.
That wouldn't cause fdarray class extension with fd types and wouldn't change
fdarray__filter() keeping the types processing outside of fdarray and libperf.
Adoption of new fdarray__poll() signature in the tool via macro (or inline
function):
#define fdarray__poll(fda, timeout) \
fdarray__poll_ext(fda, timeout, NULL, 0)
int fdarray__poll_ext(struct fdarray *fda, int timeout,
int *fds, size_t fds_size)
~Alexey
