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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 EAFDBC433DF for ; Tue, 11 Aug 2020 21:06:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BDFE2205CB for ; Tue, 11 Aug 2020 21:06:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726489AbgHKVG2 convert rfc822-to-8bit (ORCPT ); Tue, 11 Aug 2020 17:06:28 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]:21284 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726115AbgHKVG2 (ORCPT ); Tue, 11 Aug 2020 17:06:28 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-263-bL9UjMbLOpS-QdQrBdhE5A-1; Tue, 11 Aug 2020 22:06:24 +0100 X-MC-Unique: bL9UjMbLOpS-QdQrBdhE5A-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Tue, 11 Aug 2020 22:06:23 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Tue, 11 Aug 2020 22:06:23 +0100 From: David Laight To: 'Andi Kleen' CC: Peter Zijlstra , Alexander Shishkin , Arnaldo Carvalho de Melo , Ingo Molnar , "linux-kernel@vger.kernel.org" , Jiri Olsa , "alexey.budankov@linux.intel.com" , "adrian.hunter@intel.com" Subject: RE: [PATCH 1/2] perf: Add closing sibling events' file descriptors Thread-Topic: [PATCH 1/2] perf: Add closing sibling events' file descriptors Thread-Index: AQHWb+1snIoIlGwKoUSHzUM68Tmsxaky+9RQgAAnAgCAAEM5sA== Date: Tue, 11 Aug 2020 21:06:23 +0000 Message-ID: <457dfe5709e642bd9b462f4c36e8ed75@AcuMS.aculab.com> References: <20200708151635.81239-1-alexander.shishkin@linux.intel.com> <20200708151635.81239-2-alexander.shishkin@linux.intel.com> <20200806083530.GV2674@hirez.programming.kicks-ass.net> <20200806153205.GA1448395@tassilo.jf.intel.com> <875z9q1u3g.fsf@ashishki-desk.ger.corp.intel.com> <20200810144518.GB1448395@tassilo.jf.intel.com> <20200810203632.GF3982@worktop.programming.kicks-ass.net> <20200811142955.GC1448395@tassilo.jf.intel.com> <9ff26c5231954e65bbd4873d54ebd727@AcuMS.aculab.com> <20200811180334.GH1448395@tassilo.jf.intel.com> In-Reply-To: <20200811180334.GH1448395@tassilo.jf.intel.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Tue, Aug 11, 2020 at 02:47:03PM +0000, David Laight wrote: > > From: Andi Kleen > > > On Mon, Aug 10, 2020 at 10:36:32PM +0200, Peter Zijlstra wrote: > > > > On Mon, Aug 10, 2020 at 07:45:18AM -0700, Andi Kleen wrote: > > > > > > > > > Unfortunately we're kind of stuck with the old NFILE=1024 default > > > > > even though it makes little sense on modern servers. > > > > > > > > Why can't that be changed? It seems to me all of userspace changes all > > > > the time; heck that system-doofus thing flushed 20+ years of sysadmin > > > > experience down the drain, just cause. Why can't we up a file limit? > > > > > > We could try, but I believe it's hard coded in various places outside > > > the kernel. > > > > The place it really bites is select(). > > Although the kernel supports large bitmaps glibc doesn't. > > The random bit overwrites are a PITA to debug. > > Good point. > > I remember I asked for a simple define to increase like glibc5 had, but > they still didn't implement that. Even windows lets you redefine FDSET_SIZE before including the header. And their select() is much more like poll() - so the limit is the number of sockets, not the highest socket number (which do happen to be small integers). David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)