From nobody Sat Dec 27 20:54:18 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6500149F6D for ; Fri, 15 Dec 2023 17:44:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 4603F1063; Fri, 15 Dec 2023 09:45:18 -0800 (PST) Received: from merodach.members.linode.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 55FA73F5A1; Fri, 15 Dec 2023 09:44:30 -0800 (PST) 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, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, Babu Moger Subject: [PATCH v8 10/24] x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid Date: Fri, 15 Dec 2023 17:43:29 +0000 Message-Id: <20231215174343.13872-11-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20231215174343.13872-1-james.morse@arm.com> References: <20231215174343.13872-1-james.morse@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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_CLOSID 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 Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Babu Moger Reviewed-by: Shaopeng Tan Reviewed-by: Reinette Chatre Reviewed-by: Babu Moger --- Changes since v4: * Dropped stale section from comment Changes since v5: * Renamed some variables. Changes since v7: * Made comments over closid_num_dirty_rmid() not a kdoc comment. --- arch/x86/kernel/cpu/resctrl/internal.h | 2 ++ arch/x86/kernel/cpu/resctrl/monitor.c | 47 +++++++++++++++++++++++++- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 ++++++++--- 3 files changed, 62 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/r= esctrl/internal.h index 2f1d4f141dab..521afa016b05 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -568,5 +568,7 @@ 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 6dfc68c800c8..fdbef88ff39b 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -50,7 +50,7 @@ struct rmid_entry { */ static LIST_HEAD(rmid_free_lru); =20 -/** +/* * @closid_num_dirty_rmid The number of dirty RMID each CLOSID has. * Only allocated when CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID is define= d. * Indexed by CLOSID. Protected by rdtgroup_mutex. @@ -386,6 +386,51 @@ 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. + */ +int resctrl_find_cleanest_closid(void) +{ + u32 cleanest_closid =3D ~0; + 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++) { + int num_dirty; + + if (closid_allocated(i)) + continue; + + num_dirty =3D closid_num_dirty_rmid[i]; + if (num_dirty =3D=3D 0) + return i; + + if (cleanest_closid =3D=3D ~0) + cleanest_closid =3D i; + + if (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 f6b52415ca3d..00f830f729b3 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -137,13 +137,22 @@ static void closid_init(void) =20 static int closid_alloc(void) { - u32 closid =3D ffs(closid_free_map); + int cleanest_closid; + u32 closid; =20 lockdep_assert_held(&rdtgroup_mutex); =20 - if (closid =3D=3D 0) - return -ENOSPC; - closid--; + if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) { + cleanest_closid =3D resctrl_find_cleanest_closid(); + if (cleanest_closid < 0) + return cleanest_closid; + closid =3D cleanest_closid; + } else { + closid =3D ffs(closid_free_map); + if (closid =3D=3D 0) + return -ENOSPC; + closid--; + } __clear_bit(closid, &closid_free_map); =20 return closid; @@ -163,7 +172,7 @@ 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) { lockdep_assert_held(&rdtgroup_mutex); =20 --=20 2.20.1