From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v8 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Date: Sat, 25 Jan 2020 12:19:31 +0100 Message-ID: <20200125111931.GW11457@worktop.programming.kicks-ass.net> References: <20191230194042.67789-5-alex.kogan@oracle.com> <20200121132949.GL14914@hirez.programming.kicks-ass.net> <3862F8A1-FF9B-40AD-A88E-2C0BA7AF6F58@oracle.com> <20200124075235.GX14914@hirez.programming.kicks-ass.net> <2c6741c5-d89d-4b2c-cebe-a7c7f6eed884@redhat.com> <48ce49e5-98a7-23cd-09f4-8290a65abbb5@redhat.com> <8D3AFB47-B595-418C-9568-08780DDC58FF@oracle.com> <714892cd-d96f-4d41-ae8b-d7b7642a6e3c@redhat.com> <1669BFDE-A1A5-4ED8-B586-035460BBF68A@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <1669BFDE-A1A5-4ED8-B586-035460BBF68A@oracle.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane-mx.org@lists.infradead.org To: Alex Kogan Cc: linux-arch@vger.kernel.org, Hanjun Guo , Arnd Bergmann , dave.dice@oracle.com, Jan Glauber , x86@kernel.org, Will Deacon , linux@armlinux.org.uk, Steven Sistare , linux-kernel@vger.kernel.org, Ingo Molnar , Borislav Petkov , hpa@zytor.com, Waiman Long , Thomas Gleixner , Daniel Jordan , linux-arm-kernel List-Id: linux-arch.vger.kernel.org T24gRnJpLCBKYW4gMjQsIDIwMjAgYXQgMDE6MTk6MDVQTSAtMDUwMCwgQWxleCBLb2dhbiB3cm90 ZToKCj4gSXMgdGhlcmUgYSBsaWdodHdlaWdodCB3YXkgdG8gaWRlbnRpZnkgc3VjaCBhIOKAnHBy aW9yaXRpemVk4oCdIHRocmVhZD8KCk5vOyBwZW9wbGUgbWlnaHQgZm9yIGluc3RhbmNlIGNhcmUg YWJvdXQgdGFpbCBsYXRlbmNpZXMgYmV0d2VlbiB0aGVpcgppZGVudGljYWxseSBzcGVjJ2VkIHdv cmtlciB0YXNrcy4KCkluIGdlbmVyYWwgaXQgdHVybnMgb3V0IHRoYXQgcHJpb3JpdHkgaXMgYSBk eW5hbWljIGNvbmNlcHQsIG5vdCBhIHN0YXRpYwpvbmUuCgpfX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fXwpsaW51eC1hcm0ta2VybmVsIG1haWxpbmcgbGlzdAps aW51eC1hcm0ta2VybmVsQGxpc3RzLmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVh ZC5vcmcvbWFpbG1hbi9saXN0aW5mby9saW51eC1hcm0ta2VybmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from merlin.infradead.org ([205.233.59.134]:50382 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725767AbgAYLUJ (ORCPT ); Sat, 25 Jan 2020 06:20:09 -0500 Date: Sat, 25 Jan 2020 12:19:31 +0100 From: Peter Zijlstra Subject: Re: [PATCH v8 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Message-ID: <20200125111931.GW11457@worktop.programming.kicks-ass.net> References: <20191230194042.67789-5-alex.kogan@oracle.com> <20200121132949.GL14914@hirez.programming.kicks-ass.net> <3862F8A1-FF9B-40AD-A88E-2C0BA7AF6F58@oracle.com> <20200124075235.GX14914@hirez.programming.kicks-ass.net> <2c6741c5-d89d-4b2c-cebe-a7c7f6eed884@redhat.com> <48ce49e5-98a7-23cd-09f4-8290a65abbb5@redhat.com> <8D3AFB47-B595-418C-9568-08780DDC58FF@oracle.com> <714892cd-d96f-4d41-ae8b-d7b7642a6e3c@redhat.com> <1669BFDE-A1A5-4ED8-B586-035460BBF68A@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1669BFDE-A1A5-4ED8-B586-035460BBF68A@oracle.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Alex Kogan Cc: Waiman Long , linux@armlinux.org.uk, Ingo Molnar , Will Deacon , Arnd Bergmann , linux-arch@vger.kernel.org, linux-arm-kernel , linux-kernel@vger.kernel.org, Thomas Gleixner , Borislav Petkov , hpa@zytor.com, x86@kernel.org, Hanjun Guo , Jan Glauber , Steven Sistare , Daniel Jordan , dave.dice@oracle.com Message-ID: <20200125111931.Oko7HgysHgWVZ-48MsqcejEtrUe5TMkAwkNxFdlWfTY@z> On Fri, Jan 24, 2020 at 01:19:05PM -0500, Alex Kogan wrote: > Is there a lightweight way to identify such a “prioritized” thread? No; people might for instance care about tail latencies between their identically spec'ed worker tasks. In general it turns out that priority is a dynamic concept, not a static one.