Messages in this thread | | | Date | Mon, 8 Jun 2020 18:07:58 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH v7 01/13] tools/libperf: introduce notion of static polled file descriptors |
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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.budankov@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, I'm not sure why you think this is needed
I'm busy with other things this week, but I think I can come up with some patch early next week if needed
jirka
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