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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 25A63C433FE for ; Wed, 9 Nov 2022 12:45:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=6PDpGegQd1kiANaJGO6i1e5xf2B+Rm7ScKk4PPnmjVk=; b=cAX2VfTYdsva7L h1SL3b9E+S/+ELhkE66U8S9wrgXb1/hfsdfJGaKV0VGyXXn4TbJLkDduz5MXFpESK2PlrismA6H+T sAo3zIU0CgbcJcWszLTS2uiyxYq8UMRH4XYBl80fp+ZeCMj32RIQRq50K/ZcyVi5IcpWX1F4d2MZj mbM6GI3/xe65C26rruIVfUgtPjBpbPb5S/XGsAwrq+OyL1kkqtsjwl+IlFlqPzRFZbPONdg9QzRjY RgnyzLmonjCxdm4/6he4bVSQpACJXpq4bcIDVttNYouCYN0387q9S8IRws9mfMpioWPAugJbtaXZ7 yxrILLyOJFus+2Y2x21A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oskR0-00DT09-Ga; Wed, 09 Nov 2022 12:44:02 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oskQx-00DSyE-2I for linux-arm-kernel@lists.infradead.org; Wed, 09 Nov 2022 12:44:00 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id AF9EAB81E2B; Wed, 9 Nov 2022 12:43:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C010C43470; Wed, 9 Nov 2022 12:43:55 +0000 (UTC) Date: Wed, 9 Nov 2022 12:43:51 +0000 From: Catalin Marinas To: Yunfeng Ye Cc: will@kernel.org, wangkefeng.wang@huawei.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linfeilong@huawei.com Subject: Re: [PATCH 4/5] arm64: mm: Support ASID isolation feature Message-ID: References: <20221017083203.3690346-1-yeyunfeng@huawei.com> <20221017083203.3690346-5-yeyunfeng@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20221017083203.3690346-5-yeyunfeng@huawei.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221109_044359_264468_0DDA6E95 X-CRM114-Status: GOOD ( 15.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Oct 17, 2022 at 04:32:02PM +0800, Yunfeng Ye wrote: > After a rollover, the global generation will be flushed, which will > cause the process mm->context.id on all CPUs do not match the > generation. Thus, the process will compete for the global spinlock lock > to reallocate a new ASID and refresh the TLBs of all CPUs on context > switch. This will lead to the increase of scheduling delay and TLB miss. > > In some delay-sensitive scenarios, for example, part of CPUs are > isolated, only a limited number of processes are deployed to run on the > isolated CPUs. In this case, we do not want these key processes to be > affected by the rollover of ASID. Part of this commit log should also go in the cover letter and it would help to back this up by some numbers, e.g. what percentage improvement you get with this patchset by running hackbench on an isolated CPU. In theory it looks like CPU isolation would benefit from this patchset but we try not to touch this code often, so any modification should come with proper justification, backed by numbers. Note that I haven't reviewed the algorithm you are proposing in detail, only had a brief look. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel