From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55A48C433E0 for ; Mon, 8 Jun 2020 15:05:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 33DF02074B for ; Mon, 8 Jun 2020 15:05:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730165AbgFHPFz (ORCPT ); Mon, 8 Jun 2020 11:05:55 -0400 Received: from mga17.intel.com ([192.55.52.151]:54929 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730033AbgFHPFz (ORCPT ); Mon, 8 Jun 2020 11:05:55 -0400 IronPort-SDR: r5+z+c0js2ENdqaQ7ZqT1joNeQrMS12ndT2thXf94/lHgHLKaZvvL1qNJ3nIG1IPeK8AhVTXjG m+UjcoFHfBwA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jun 2020 08:05:54 -0700 IronPort-SDR: LRkKkFVX9sS2/zTHW18Q9QjcZyHNOsadTvcZYrE5DbIksld+ytT8i1vRFAXlS2qpvd994YYt/p b2WgjVkhZkxg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,487,1583222400"; d="scan'208";a="259828219" Received: from linux.intel.com ([10.54.29.200]) by fmsmga008.fm.intel.com with ESMTP; 08 Jun 2020 08:05:54 -0700 Received: from [10.249.230.149] (abudanko-mobl.ccr.corp.intel.com [10.249.230.149]) by linux.intel.com (Postfix) with ESMTP id 28D36580458; Mon, 8 Jun 2020 08:05:51 -0700 (PDT) Subject: Re: [PATCH v7 01/13] tools/libperf: introduce notion of static polled file descriptors From: Alexey Budankov To: Jiri Olsa Cc: Arnaldo Carvalho de Melo , Namhyung Kim , Alexander Shishkin , Peter Zijlstra , Ingo Molnar , Andi Kleen , linux-kernel References: <5de4b954-24f0-1e8d-5a0d-7b12783b8218@linux.intel.com> <3c92a0ad-d7d3-4e78-f0b8-1d3a7122c69e@linux.intel.com> <20200605105051.GA1404794@krava> <20200605113834.GC1404794@krava> <49eca46e-4d0e-2ae5-d7d9-e37a4d680270@linux.intel.com> <20200608084344.GA1520715@krava> <2d80a43a-54cf-3d12-92fd-066217c95d76@linux.intel.com> Organization: Intel Corp. Message-ID: Date: Mon, 8 Jun 2020 18:05:51 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.8.1 MIME-Version: 1.0 In-Reply-To: <2d80a43a-54cf-3d12-92fd-066217c95d76@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.06.2020 12:54, 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 >>>>>>> --- >>>>>>> + 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); Are there any thoughts regarding this? ~Alexey