From: Leonardo Bras <leonardo@linux.ibm.com> To: Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, Arnd Bergmann <arnd@arndb.de>, Andrew Morton <akpm@linux-foundation.org>, "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>, Nicholas Piggin <npiggin@gmail.com>, Christophe Leroy <christophe.leroy@c-s.fr>, Steven Price <steven.price@arm.com>, Robin Murphy <robin.murphy@arm.com>, Leonardo Bras <leonardo@linux.ibm.com>, Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>, Balbir Singh <bsingharora@gmail.com>, Reza Arbab <arbab@linux.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Allison Randal <allison@lohutok.net>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Mike Rapoport <rppt@linux.ibm.com>, Michal Suchanek <msuchanek@su> Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v6 11/11] powerpc/mm/book3s64/pgtable: Uses counting method to skip serializing Date: Thu, 6 Feb 2020 00:09:00 -0300 [thread overview] Message-ID: <20200206030900.147032-12-leonardo@linux.ibm.com> (raw) In-Reply-To: <20200206030900.147032-1-leonardo@linux.ibm.com> For each cpu in cpumask, checks if it's running a lockless pagetable walk. Then, run serialize_against_pte_lookup() only on these cpus. serialize_agains_pte_lookup() can take a long while when there are a lot of cpus in cpumask. This method is intended to reduce this waiting, while not impacting too much on the lockless pagetable walk. Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> --- arch/powerpc/mm/book3s64/pgtable.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c index bb138b628f86..4822ff1aac4b 100644 --- a/arch/powerpc/mm/book3s64/pgtable.c +++ b/arch/powerpc/mm/book3s64/pgtable.c @@ -96,8 +96,22 @@ static DEFINE_PER_CPU(int, lockless_pgtbl_walk_counter); */ void serialize_against_pte_lookup(struct mm_struct *mm) { + int cpu; + struct cpumask cm; + smp_mb(); - smp_call_function_many(mm_cpumask(mm), do_nothing, NULL, 1); + + /* + * Fills a new cpumask only with cpus that are currently doing a + * lockless pagetable walk. This reduces time spent in this function. + */ + cpumask_clear(&cm); + for_each_cpu(cpu, mm_cpumask((mm))) { + if (per_cpu(lockless_pgtbl_walk_counter, cpu) > 0) + cpumask_set_cpu(cpu, &cm); + } + + smp_call_function_many(&cm, do_nothing, NULL, 1); } /* begin_lockless_pgtbl_walk: Must be inserted before a function call that does -- 2.24.1
WARNING: multiple messages have this Message-ID (diff)
From: Leonardo Bras <leonardo@linux.ibm.com> To: Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, Arnd Bergmann <arnd@arndb.de>, Andrew Morton <akpm@linux-foundation.org>, "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>, Nicholas Piggin <npiggin@gmail.com>, Christophe Leroy <christophe.leroy@c-s.fr>, Steven Price <steven.price@arm.com>, Robin Murphy <robin.murphy@arm.com>, Leonardo Bras <leonardo@linux.ibm.com>, Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>, Balbir Singh <bsingharora@gmail.com>, Reza Arbab <arbab@linux.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Allison Randal <allison@lohutok.net>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Mike Rapoport <rppt@linux.ibm.com>, Michal Suchanek <msuchanek@suse.de> Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v6 11/11] powerpc/mm/book3s64/pgtable: Uses counting method to skip serializing Date: Thu, 6 Feb 2020 00:09:00 -0300 [thread overview] Message-ID: <20200206030900.147032-12-leonardo@linux.ibm.com> (raw) Message-ID: <20200206030900.uiAsp0cVDLzvYRwZV3jm2x2ulm-eddrUMvis0jHRNZc@z> (raw) In-Reply-To: <20200206030900.147032-1-leonardo@linux.ibm.com> For each cpu in cpumask, checks if it's running a lockless pagetable walk. Then, run serialize_against_pte_lookup() only on these cpus. serialize_agains_pte_lookup() can take a long while when there are a lot of cpus in cpumask. This method is intended to reduce this waiting, while not impacting too much on the lockless pagetable walk. Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> --- arch/powerpc/mm/book3s64/pgtable.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c index bb138b628f86..4822ff1aac4b 100644 --- a/arch/powerpc/mm/book3s64/pgtable.c +++ b/arch/powerpc/mm/book3s64/pgtable.c @@ -96,8 +96,22 @@ static DEFINE_PER_CPU(int, lockless_pgtbl_walk_counter); */ void serialize_against_pte_lookup(struct mm_struct *mm) { + int cpu; + struct cpumask cm; + smp_mb(); - smp_call_function_many(mm_cpumask(mm), do_nothing, NULL, 1); + + /* + * Fills a new cpumask only with cpus that are currently doing a + * lockless pagetable walk. This reduces time spent in this function. + */ + cpumask_clear(&cm); + for_each_cpu(cpu, mm_cpumask((mm))) { + if (per_cpu(lockless_pgtbl_walk_counter, cpu) > 0) + cpumask_set_cpu(cpu, &cm); + } + + smp_call_function_many(&cm, do_nothing, NULL, 1); } /* begin_lockless_pgtbl_walk: Must be inserted before a function call that does -- 2.24.1
next prev parent reply other threads:[~2020-02-06 3:09 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-06 3:08 [PATCH v6 00/11] Introduces new functions for tracking lockless pagetable walks Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 3:08 ` [PATCH v6 01/11] asm-generic/pgtable: Adds generic functions to track lockless pgtable walks Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 5:54 ` Christophe Leroy 2020-02-06 5:54 ` Christophe Leroy 2020-02-07 2:19 ` Leonardo Bras 2020-02-07 2:19 ` Leonardo Bras 2020-02-07 5:39 ` kbuild test robot 2020-02-07 5:39 ` kbuild test robot 2020-02-06 3:08 ` [PATCH v6 02/11] mm/gup: Use functions to track lockless pgtbl walks on gup_pgd_range Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 3:25 ` Leonardo Bras 2020-02-06 3:25 ` Leonardo Bras 2020-02-07 22:54 ` John Hubbard 2020-02-07 22:54 ` John Hubbard 2020-02-17 20:55 ` Leonardo Bras 2020-02-17 20:55 ` Leonardo Bras 2020-10-15 14:46 ` Michal Suchánek 2020-10-16 3:27 ` Aneesh Kumar K.V 2020-02-07 1:19 ` kbuild test robot 2020-02-07 1:19 ` kbuild test robot 2020-02-07 8:01 ` kbuild test robot 2020-02-07 8:01 ` kbuild test robot 2020-02-06 3:08 ` [PATCH v6 03/11] powerpc/mm: Adds arch-specificic functions to track lockless pgtable walks Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 5:46 ` Christophe Leroy 2020-02-06 5:46 ` Christophe Leroy 2020-02-07 4:38 ` Leonardo Bras 2020-02-07 4:38 ` Leonardo Bras 2020-02-17 20:32 ` Leonardo Bras 2020-02-17 20:32 ` Leonardo Bras 2020-02-06 3:08 ` [PATCH v6 04/11] powerpc/mce_power: Use functions to track lockless pgtbl walks Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 5:48 ` Christophe Leroy 2020-02-06 5:48 ` Christophe Leroy 2020-02-07 4:00 ` Leonardo Bras 2020-02-07 4:00 ` Leonardo Bras 2020-02-06 3:08 ` [PATCH v6 05/11] powerpc/perf: " Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 3:08 ` [PATCH v6 06/11] powerpc/mm/book3s64/hash: " Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 6:06 ` Christophe Leroy 2020-02-06 6:06 ` Christophe Leroy 2020-02-07 3:49 ` Leonardo Bras 2020-02-07 3:49 ` Leonardo Bras 2020-02-06 3:08 ` [PATCH v6 07/11] powerpc/kvm/e500: " Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 6:18 ` Christophe Leroy 2020-02-06 6:18 ` Christophe Leroy 2020-02-07 3:10 ` Leonardo Bras 2020-02-07 3:10 ` Leonardo Bras 2020-02-06 3:08 ` [PATCH v6 08/11] powerpc/kvm/book3s_hv: " Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 3:08 ` [PATCH v6 09/11] powerpc/kvm/book3s_64: " Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 3:08 ` [PATCH v6 10/11] powerpc/mm: Adds counting method to track lockless pagetable walks Leonardo Bras 2020-02-06 3:08 ` Leonardo Bras 2020-02-06 6:23 ` Christophe Leroy 2020-02-06 6:23 ` Christophe Leroy 2020-02-07 1:56 ` Leonardo Bras 2020-02-07 1:56 ` Leonardo Bras 2020-02-06 3:09 ` Leonardo Bras [this message] 2020-02-06 3:09 ` [PATCH v6 11/11] powerpc/mm/book3s64/pgtable: Uses counting method to skip serializing Leonardo Bras
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