On 03.06.2020 18:53, Adrian Hunter wrote: > On 3/06/20 3:52 pm, Alexey Budankov wrote: >> >> On 03.06.2020 15:30, Hunter, Adrian wrote: >>> >>> >>>> -----Original Message----- >>>> From: Hunter, Adrian <adrian.hun...@intel.com> >>>> Sent: Wednesday, June 3, 2020 3:24 PM >>>> To: Alexey Budankov <alexey.budan...@linux.intel.com> >>>> Cc: Arnaldo Carvalho de Melo <a...@kernel.org>; Jiri Olsa >>>> <jo...@redhat.com>; Namhyung Kim <namhy...@kernel.org>; Alexander >>>> Shishkin <alexander.shish...@linux.intel.com>; Peter Zijlstra >>>> <pet...@infradead.org>; Ingo Molnar <mi...@redhat.com>; Andi Kleen >>>> <a...@linux.intel.com>; linux-kernel <linux-kernel@vger.kernel.org> >>>> Subject: Re: [PATCH v6 01/13] tools/libperf: introduce notion of static >>>> polled >>>> file descriptors >>>> >>>> On 3/06/20 3:01 pm, Alexey Budankov wrote: >>>>> Hi, >>>>> >>>>> On 03.06.2020 14:38, Adrian Hunter wrote: >>>>>> 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. >>>>> >>>>> It then will block event consumption loop, at least in record mode, >>>>> due to change sin initial assumptions behind fdarray__filter(). So >>>>> extension of the API with 'static' fds looks safer w.r.t. possible >>>>> functional regressions at the same time extending the API with ability >>>>> to atomically wait for (poll()) not only event fds but also any other fds >>>> during monitoring. >>>> >>>> So make fdarray__filter() return the number of filterable fds remaining. >>>> >>> >>> >>> Or perhaps simpler, compare the return value to the number of fds that are >>> known not to be filterable >> >> Well, various implementations are for sure possible but the proposed design >> avoids implicit code assumptions and dependency on API calls order as in API >> implementation as in client code and that is why it's been proposed this way. >> > > The dependencies are confined one function, namely __cmd_record(), it is > simpler, and avoids the inelegant changes to fdarray__poll().
As far the changes don't cause regressions and serve their purpose well they are acceptable.
