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>,
aneesh.kumar@linux.vnet.ibm.com
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v5 15/22] powerpc/mm: Avoid useless lock with single page fragments
Date: Tue, 25 Sep 2018 16:51:08 +0000 (UTC) [thread overview]
Message-ID: <18c62230b394eee9f49832d5dbd518ba69f39a18.1537892499.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1537892498.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.
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 723cd324fa34..c43e225e124d 100644
--- a/arch/powerpc/mm/pgtable-book3s64.c
+++ b/arch/powerpc/mm/pgtable-book3s64.c
@@ -239,6 +239,9 @@ 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:[~2018-09-25 16:51 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-25 16:50 [PATCH v5 00/22] Implement use of HW assistance on TLB table walk on 8xx Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 01/22] Revert "powerpc/8xx: Use L1 entry APG to handle _PAGE_ACCESSED for CONFIG_SWAP" Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 02/22] powerpc/code-patching: add a helper to get the address of a patch_site Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 03/22] powerpc/8xx: Use patch_site for memory setup patching Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 04/22] powerpc/8xx: Use patch_site for perf counters setup Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 05/22] powerpc/8xx: Move SW perf counters in first 32kb of memory Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 06/22] powerpc/8xx: Temporarily disable 16k pages and 512k hugepages Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 07/22] powerpc/mm: Use hardware assistance in TLB handlers on the 8xx Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 08/22] powerpc/mm: Enable 512k hugepage support with HW assistance " Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 09/22] powerpc/8xx: don't use r12/SPRN_SPRG_SCRATCH2 in TLB Miss handlers Christophe Leroy
2018-09-25 16:50 ` [PATCH v5 10/22] powerpc/8xx: regroup TLB handler routines Christophe Leroy
2018-09-25 16:51 ` [PATCH v5 11/22] powerpc/mm: don't use pte_alloc_one_kernel() before slab is available Christophe Leroy
2018-09-25 16:51 ` [PATCH v5 12/22] powerpc/mm: inline pte_alloc_one() and pte_alloc_one_kernel() in PPC32 Christophe Leroy
2018-09-25 16:51 ` [PATCH v5 13/22] powerpc/book3s32: Remove CONFIG_BOOKE dependent code Christophe Leroy
2018-09-25 16:51 ` [PATCH v5 14/22] powerpc/mm: Move pte_fragment_alloc() to a common location Christophe Leroy
2018-09-26 2:43 ` Aneesh Kumar K.V
2018-09-25 16:51 ` Christophe Leroy [this message]
2018-09-26 2:43 ` [PATCH v5 15/22] powerpc/mm: Avoid useless lock with single page fragments Aneesh Kumar K.V
2018-09-25 16:51 ` [PATCH v5 16/22] powerpc/mm: move platform specific mmu-xxx.h in platform directories Christophe Leroy
2018-09-26 2:44 ` Aneesh Kumar K.V
2018-09-25 16:51 ` [PATCH v5 17/22] powerpc/mm: Move pgtable_t into platform headers Christophe Leroy
2018-09-26 2:44 ` Aneesh Kumar K.V
2018-09-25 16:51 ` [PATCH v5 18/22] powerpc/mm: Extend pte_fragment functionality to nohash/32 Christophe Leroy
2018-09-26 2:48 ` Aneesh Kumar K.V
2018-09-26 8:10 ` Christophe LEROY
2018-09-26 9:01 ` Aneesh Kumar K.V
2018-09-25 16:51 ` [PATCH v5 19/22] powerpc/8xx: Remove PTE_ATOMIC_UPDATES Christophe Leroy
2018-09-25 16:51 ` [PATCH v5 20/22] powerpc/mm: reintroduce 16K pages with HW assistance on 8xx Christophe Leroy
2018-09-25 16:51 ` [PATCH v5 21/22] powerpc/nohash32: allow setting GUARDED attribute in the PMD directly Christophe Leroy
2018-10-17 11:51 ` Christophe LEROY
2018-09-25 16:51 ` [PATCH v5 22/22] powerpc/8xx: set " Christophe Leroy
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