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)
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
prev parent reply other threads:[~2020-02-06 3:13 UTC|newest]
Thread overview: 33+ 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 ` [PATCH v6 01/11] asm-generic/pgtable: Adds generic functions to track lockless pgtable walks Leonardo Bras
2020-02-06 5:54 ` Christophe Leroy
2020-02-07 2:19 ` Leonardo Bras
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 3:25 ` Leonardo Bras
2020-02-07 22:54 ` John Hubbard
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 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 5:46 ` Christophe Leroy
2020-02-07 4:38 ` 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 5:48 ` Christophe Leroy
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 ` [PATCH v6 06/11] powerpc/mm/book3s64/hash: " Leonardo Bras
2020-02-06 6:06 ` Christophe Leroy
2020-02-07 3:49 ` Leonardo Bras
2020-02-06 3:08 ` [PATCH v6 07/11] powerpc/kvm/e500: " Leonardo Bras
2020-02-06 6:18 ` Christophe Leroy
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 ` [PATCH v6 09/11] powerpc/kvm/book3s_64: " 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 6:23 ` Christophe Leroy
2020-02-07 1:56 ` Leonardo Bras
2020-02-06 3:09 ` Leonardo Bras [this message]
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