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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 E59F7C433DF for ; Wed, 3 Jun 2020 12:24:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BDEBF20674 for ; Wed, 3 Jun 2020 12:24:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726015AbgFCMYa (ORCPT ); Wed, 3 Jun 2020 08:24:30 -0400 Received: from mga03.intel.com ([134.134.136.65]:49368 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725833AbgFCMY3 (ORCPT ); Wed, 3 Jun 2020 08:24:29 -0400 IronPort-SDR: iJiSA/R3hxng3+C3CKSTdOpOl24ETeE+ed7lyCOS9aJPrBTJp9ezFX2ZMgi7W8c/wm7HLWx3bS xnpdCfu0m3jw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jun 2020 05:24:29 -0700 IronPort-SDR: rauLYjJSv89Od8vUCODQbnDE1NI9cvg1cXbDEqABEorzr0iL0jefyZRx6syl2Kc1Zej+yWmW0Q 0q8kDRFXX8qQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,467,1583222400"; d="scan'208";a="269059367" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.157]) ([10.237.72.157]) by orsmga003.jf.intel.com with ESMTP; 03 Jun 2020 05:24:26 -0700 Subject: Re: [PATCH v6 01/13] tools/libperf: introduce notion of static polled file descriptors To: Alexey Budankov Cc: Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Alexander Shishkin , Peter Zijlstra , Ingo Molnar , Andi Kleen , linux-kernel References: <40643542-6676-e0bc-2d10-165dfde41e29@linux.intel.com> <33c91520-7040-bd6b-b176-004ddbec2a63@intel.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: Date: Wed, 3 Jun 2020 15:23:53 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: 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 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.