From nobody Mon Feb 9 12:00:59 2026 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 5F658C001E0 for ; Fri, 28 Jul 2023 16:45:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235058AbjG1QpO (ORCPT ); Fri, 28 Jul 2023 12:45:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46922 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233839AbjG1QoI (ORCPT ); Fri, 28 Jul 2023 12:44:08 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id EA52E468B for ; Fri, 28 Jul 2023 09:43:42 -0700 (PDT) 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 05E1D15DB; Fri, 28 Jul 2023 09:44:25 -0700 (PDT) Received: from merodach.members.linode.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3BF943F67D; Fri, 28 Jul 2023 09:43:39 -0700 (PDT) From: James Morse To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Fenghua Yu , Reinette Chatre , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Babu Moger , James Morse , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, xingxin.hx@openanolis.org, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com Subject: [PATCH v5 08/24] x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid Date: Fri, 28 Jul 2023 16:42:38 +0000 Message-Id: <20230728164254.27562-9-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20230728164254.27562-1-james.morse@arm.com> References: <20230728164254.27562-1-james.morse@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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. Instead of allocating the first free CLOSID, on architectures where CONFIG_RESCTRL_RMID_DEPENDS_ON_COSID is enabled, search closid_num_dirty_rmid[] to find the cleanest CLOSID. The CLOSID found is returned to closid_alloc() for the free list to be updated. Signed-off-by: James Morse --- Changes since v4: * Dropped stale section from comment --- arch/x86/kernel/cpu/resctrl/internal.h | 2 ++ arch/x86/kernel/cpu/resctrl/monitor.c | 42 ++++++++++++++++++++++++++ arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 +++++++++--- 3 files changed, 58 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/r= esctrl/internal.h index 94749ee950dd..7c2a1c235480 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -557,5 +557,7 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r); void __init thread_throttle_mode_init(void); void __init mbm_config_rftype_init(const char *config); void rdt_staged_configs_clear(void); +bool closid_allocated(unsigned int closid); +int resctrl_find_cleanest_closid(void); =20 #endif /* _ASM_X86_RESCTRL_INTERNAL_H */ diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/re= sctrl/monitor.c index 44addc0126fc..c268aa5925c7 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -379,6 +379,48 @@ static struct rmid_entry *resctrl_find_free_rmid(u32 c= losid) return ERR_PTR(-ENOSPC); } =20 +/** + * resctrl_find_cleanest_closid() - Find a CLOSID where all the associated + * RMID are clean, or the CLOSID that has + * the most clean RMID. + * + * MPAM's equivalent of RMID are per-CLOSID, meaning a freshly allocated C= LOSID + * may not be able to allocate clean RMID. To avoid this the allocator will + * choose the CLOSID with the most clean RMID. + * + * When the CLOSID and RMID are independent numbers, the first free CLOSID= will + * be returned. + */ +int resctrl_find_cleanest_closid(void) +{ + u32 cleanest_closid =3D ~0, iter_num_dirty; + int i =3D 0; + + lockdep_assert_held(&rdtgroup_mutex); + + if (!IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) + return -EIO; + + for (i =3D 0; i < closids_supported(); i++) { + if (closid_allocated(i)) + continue; + + iter_num_dirty =3D closid_num_dirty_rmid[i]; + if (iter_num_dirty =3D=3D 0) + return i; + + if (cleanest_closid =3D=3D ~0) + cleanest_closid =3D i; + + if (iter_num_dirty < closid_num_dirty_rmid[cleanest_closid]) + cleanest_closid =3D i; + } + + if (cleanest_closid =3D=3D ~0) + return -ENOSPC; + return cleanest_closid; +} + /* * For MPAM the RMID value is not unique, and has to be considered with * the CLOSID. The (CLOSID, RMID) pair is allocated on all domains, which diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/r= esctrl/rdtgroup.c index 4ab9bb018c17..df28b81d2c9c 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -132,11 +132,20 @@ static void closid_init(void) =20 static int closid_alloc(void) { - u32 closid =3D ffs(closid_free_map); + u32 closid; + int err; =20 - if (closid =3D=3D 0) - return -ENOSPC; - closid--; + if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) { + err =3D resctrl_find_cleanest_closid(); + if (err < 0) + return err; + closid =3D err; + } else { + closid =3D ffs(closid_free_map); + if (closid =3D=3D 0) + return -ENOSPC; + closid--; + } clear_bit(closid, &closid_free_map); =20 return closid; @@ -154,7 +163,7 @@ void closid_free(int closid) * Return: true if @closid is currently associated with a resource group, * false if @closid is free */ -static bool closid_allocated(unsigned int closid) +bool closid_allocated(unsigned int closid) { return !test_bit(closid, &closid_free_map); } --=20 2.39.2