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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5AD26C433DF for ; Mon, 8 Jun 2020 16:11:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E544206D5 for ; Mon, 8 Jun 2020 16:11:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="YKFJ+YlI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730417AbgFHQLD (ORCPT ); Mon, 8 Jun 2020 12:11:03 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:46649 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730336AbgFHQLC (ORCPT ); Mon, 8 Jun 2020 12:11:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591632659; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=bdZ/FO3JVy4bIYn2TPHRqZsWVlijIn0vFcgA+I8jpF4=; b=YKFJ+YlIKqq7ILCVR3xidXFgFvjs6VMVHJT/lBQqC95nWAbIFdTsezNNMDMuY2mUYLDfMe PsgMaqiZBRTMey6jR7bUzkq1KWnlT0EQnLw/50JV9sLy1aXakYp3YPZNJTusqOgQ4Oyx5X xqkReYxGAEDP2yV2nDcvxYSCu5B/PMY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-475-YbkROfZTNS28D4IB7EIA_Q-1; Mon, 08 Jun 2020 12:10:50 -0400 X-MC-Unique: YbkROfZTNS28D4IB7EIA_Q-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 35EC91902EC0; Mon, 8 Jun 2020 16:08:01 +0000 (UTC) Received: from krava (unknown [10.40.192.143]) by smtp.corp.redhat.com (Postfix) with SMTP id 355D87F0BE; Mon, 8 Jun 2020 16:07:59 +0000 (UTC) Date: Mon, 8 Jun 2020 18:07:58 +0200 From: Jiri Olsa To: Alexey Budankov Cc: Arnaldo Carvalho de Melo , Namhyung Kim , Alexander Shishkin , Peter Zijlstra , Ingo Molnar , Andi Kleen , linux-kernel Subject: Re: [PATCH v7 01/13] tools/libperf: introduce notion of static polled file descriptors Message-ID: <20200608160758.GD1558310@krava> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2d80a43a-54cf-3d12-92fd-066217c95d76@linux.intel.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > >>>>>> --- > >>>>>> 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