From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v8 04/20] powerpc/mm: Avoid useless lock with single page fragments
Date: Thu, 29 Nov 2018 08:10:11 +0000 (UTC) [thread overview]
Message-ID: <6acfdaf9ca44737cfd0dfec8fc9157e5838f7ce9.1543478200.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1543478199.git.christophe.leroy@c-s.fr>
There is no point in taking the page table lock as pte_frag or
pmd_frag are always NULL when we have only one fragment.
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/mm/pgtable-book3s64.c | 3 +++
arch/powerpc/mm/pgtable-frag.c | 3 +++
2 files changed, 6 insertions(+)
diff --git a/arch/powerpc/mm/pgtable-book3s64.c b/arch/powerpc/mm/pgtable-book3s64.c
index 0c0fd173208a..f3c31f5e1026 100644
--- a/arch/powerpc/mm/pgtable-book3s64.c
+++ b/arch/powerpc/mm/pgtable-book3s64.c
@@ -244,6 +244,9 @@ static pmd_t *get_pmd_from_cache(struct mm_struct *mm)
{
void *pmd_frag, *ret;
+ if (PMD_FRAG_NR == 1)
+ return NULL;
+
spin_lock(&mm->page_table_lock);
ret = mm->context.pmd_frag;
if (ret) {
diff --git a/arch/powerpc/mm/pgtable-frag.c b/arch/powerpc/mm/pgtable-frag.c
index d61e7c2a9a79..7544d0d7177d 100644
--- a/arch/powerpc/mm/pgtable-frag.c
+++ b/arch/powerpc/mm/pgtable-frag.c
@@ -34,6 +34,9 @@ static pte_t *get_pte_from_cache(struct mm_struct *mm)
{
void *pte_frag, *ret;
+ if (PTE_FRAG_NR == 1)
+ return NULL;
+
spin_lock(&mm->page_table_lock);
ret = mm->context.pte_frag;
if (ret) {
--
2.13.3
next prev parent reply other threads:[~2018-11-29 8:10 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-29 8:10 [PATCH v8 00/20] Implement use of HW assistance on TLB table walk on 8xx Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 01/20] powerpc/book3s32: Remove CONFIG_BOOKE dependent code Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 02/20] powerpc/8xx: Remove PTE_ATOMIC_UPDATES Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 03/20] powerpc/mm: Move pte_fragment_alloc() to a common location Christophe Leroy
2018-11-29 8:10 ` Christophe Leroy [this message]
2018-11-29 8:10 ` [PATCH v8 05/20] powerpc/mm: move platform specific mmu-xxx.h in platform directories Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 06/20] powerpc/mm: Move pgtable_t into platform headers Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 07/20] powerpc/mm: add helpers to get/set mm.context->pte_frag Christophe Leroy
2018-11-29 18:26 ` kbuild test robot
2018-11-29 8:10 ` [PATCH v8 08/20] powerpc/mm: Extend pte_fragment functionality to PPC32 Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 09/20] powerpc/mm: enable the use of page table cache of order 0 Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 10/20] powerpc/mm: replace hugetlb_cache by PGT_CACHE(PTE_T_ORDER) Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 11/20] powerpc/mm: fix a warning when a cache is common to PGD and hugepages Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 12/20] powerpc/mm: remove unnecessary test in pgtable_cache_init() Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 13/20] powerpc/8xx: Move SW perf counters in first 32kb of memory Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 14/20] powerpc/8xx: Temporarily disable 16k pages and hugepages Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 15/20] powerpc/8xx: Use hardware assistance in TLB handlers Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 16/20] powerpc/8xx: Enable 8M hugepage support with HW assistance Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 17/20] powerpc/8xx: Enable 512k " Christophe Leroy
2018-11-29 19:07 ` kbuild test robot
2018-11-29 8:10 ` [PATCH v8 18/20] powerpc/8xx: reintroduce 16K pages " Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 19/20] powerpc/8xx: don't use r12/SPRN_SPRG_SCRATCH2 in TLB Miss handlers Christophe Leroy
2018-11-29 8:10 ` [PATCH v8 20/20] powerpc/8xx: regroup TLB handler routines Christophe Leroy
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