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 4747DC4332F for ; Wed, 9 Nov 2022 17:04:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231321AbiKIREG (ORCPT ); Wed, 9 Nov 2022 12:04:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36868 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231738AbiKIRDg (ORCPT ); Wed, 9 Nov 2022 12:03:36 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8D5E929C8A for ; Wed, 9 Nov 2022 09:02:51 -0800 (PST) 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 56F871FB; Wed, 9 Nov 2022 09:02:56 -0800 (PST) Received: from [10.1.197.38] (eglon.cambridge.arm.com [10.1.197.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 97F603F534; Wed, 9 Nov 2022 09:02:46 -0800 (PST) Message-ID: Date: Wed, 9 Nov 2022 17:02:40 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [PATCH 06/18] x86/resctrl: Allow the allocator to check if a CLOSID can allocate clean RMID Content-Language: en-GB To: Shawn Wang , x86@kernel.org, linux-kernel@vger.kernel.org Cc: Fenghua Yu , Reinette Chatre , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Babu Moger , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, Jamie Iles , Xin Hao , xingxin.hx@openanolis.org, baolin.wang@linux.alibaba.com, peternewman@google.com References: <20221021131204.5581-1-james.morse@arm.com> <20221021131204.5581-7-james.morse@arm.com> From: James Morse In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Shawn, On 08/11/2022 15:57, Shawn Wang wrote: > On 10/21/2022 9:11 PM, James Morse wrote: >> MPAM's PMG bits extend its PARTID space, meaning the same PMG value can be >> used for different control groups. >> >> This means once a CLOSID is allocated, all its monitoring ids may still be >> dirty, and held in limbo. >> >> Add a helper to allow the CLOSID allocator to check if a CLOSID has dirty >> RMID values. This behaviour is enabled by a kconfig option selected by >> the architecture, which avoids a pointless search for x86. >> +/** >> + * resctrl_closid_is_dirty - Determine if clean RMID can be allocate for this >> + *                           CLOSID. >> + * @closid: The CLOSID that is being queried. >> + * >> + * MPAM's equivalent of RMID are per-CLOSID, meaning a freshly allocate CLOSID >> + * may not be able to allocate clean RMID. To avoid this the allocator will >> + * only return clean CLOSID. >> + */ >> +bool resctrl_closid_is_dirty(u32 closid) >> +{ >> +    struct rmid_entry *entry; >> +    int i; >> + >> +    lockdep_assert_held(&rdtgroup_mutex); >> + >> +    if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) >> +        return false; > > Since dirty closid occurs when the kconfig option for MPAM is enabled, it seems > that the condition of the if statement here should take the opposite value: >     if (!IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) Yup. Bother. Thanks for spotting that! It was intended to avoid this work on x86 as its pointless, and the number of RMID could be large. Thanks! James