From nobody Mon Feb 9 03:45:28 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 A6BF0C7EE29 for ; Thu, 25 May 2023 18:03:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240568AbjEYSDY (ORCPT ); Thu, 25 May 2023 14:03:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240778AbjEYSDF (ORCPT ); Thu, 25 May 2023 14:03:05 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 11B20E6B for ; Thu, 25 May 2023 11:02:54 -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 83A2B1655; Thu, 25 May 2023 11:03:39 -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 B9D7E3F6C4; Thu, 25 May 2023 11:02:51 -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 v4 08/24] x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid Date: Thu, 25 May 2023 18:01:53 +0000 Message-Id: <20230525180209.19497-9-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20230525180209.19497-1-james.morse@arm.com> References: <20230525180209.19497-1-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 --- arch/x86/kernel/cpu/resctrl/internal.h | 2 ++ arch/x86/kernel/cpu/resctrl/monitor.c | 45 ++++++++++++++++++++++++++ arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 ++++++++--- 3 files changed, 61 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/r= esctrl/internal.h index 23e20f89d2b3..96fb7658ff74 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 1e7fa40ee471..128d4c7206e4 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -379,6 +379,51 @@ 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. + * + * Call when CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID is defined. If not, call + * resctrl_closid_alloc_first_free() instead. + */ +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 6bf5623f82b4..1120c7700126 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