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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98B83C433F5 for ; Tue, 11 Jan 2022 11:05:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238380AbiAKLFQ (ORCPT ); Tue, 11 Jan 2022 06:05:16 -0500 Received: from foss.arm.com ([217.140.110.172]:44722 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238096AbiAKLFO (ORCPT ); Tue, 11 Jan 2022 06:05:14 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 17A9E1FB; Tue, 11 Jan 2022 03:05:14 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.1.156]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A49723F766; Tue, 11 Jan 2022 03:05:12 -0800 (PST) Date: Tue, 11 Jan 2022 11:05:06 +0000 From: Mark Rutland To: He Ying Cc: catalin.marinas@arm.com, will@kernel.org, marcan@marcan.st, maz@kernel.org, joey.gouly@arm.com, pcc@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: Make CONFIG_ARM64_PSEUDO_NMI macro wrap all the pseudo-NMI code Message-ID: References: <20220107085536.214501-1-heying24@huawei.com> <168f7e83-e815-f10e-3a43-8529aab77f1e@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <168f7e83-e815-f10e-3a43-8529aab77f1e@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 11, 2022 at 04:52:32PM +0800, He Ying wrote: > 在 2022/1/10 19:26, Mark Rutland 写道: > > On Mon, Jan 10, 2022 at 11:00:43AM +0800, He Ying wrote: > > > 在 2022/1/7 21:19, Mark Rutland 写道: > > > > On Fri, Jan 07, 2022 at 03:55:36AM -0500, He Ying wrote: > > Due to the large numbers, I suspect this must be due to a specific fast-path, > > and it's possible that this is due to secondary factors (e.g. alignment of > > code) rather than the pseudo-NMK code itself. > > > > We need to narrow down *where* time is being spent. Since it appears that this > > is related to the local IRQ state management, it isn't likely that we can > > determine that reliably with the PMU. Given that, I think the first step is to > > reproduce the result elsewhere, for which we will need some plublicly available > > test-case. > > As said before, I asked our collegues how they did the ARP test. In one word, > a very small performance regression may bring the big change to the test > result. > > I feel very sorry for missing this important information. So, this patch may > improve the performance a little and then lead to the big change to the > test result. No problem; thanks for confirming. [...] > OK, I see. What do you think if I send a v2 patch that only adds ifdeffery > to > > arch/arm64/kernel/entry.S and leave the rework to ALERNATIVE behind? I think that would be reasonable given we do that for other bits in entry.S; I'd be happy with such a patch. Thanks, Mark.