From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v3 3/3] x86/mm: If INVPCID is available, use it to flush global mappings
Date: Fri, 29 Jan 2016 11:42:59 -0800 [thread overview]
Message-ID: <ed0ef62581c0ea9c99b9bf6df726015e96d44743.1454096309.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1454096309.git.luto@kernel.org>
In-Reply-To: <cover.1454096309.git.luto@kernel.org>
On my Skylake laptop, INVPCID function 2 (flush absolutely
everything) takes about 376ns, whereas saving flags, twiddling
CR4.PGE to flush global mappings, and restoring flags takes about
539ns.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/include/asm/tlbflush.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 8b576832777e..985f1162c505 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -152,6 +152,15 @@ static inline void __native_flush_tlb_global(void)
{
unsigned long flags;
+ if (static_cpu_has_safe(X86_FEATURE_INVPCID)) {
+ /*
+ * Using INVPCID is considerably faster than a pair of writes
+ * to CR4 sandwiched inside an IRQ flag save/restore.
+ */
+ invpcid_flush_all();
+ return;
+ }
+
/*
* Read-modify-write to CR4 - protect it from preemption and
* from interrupts. (Use the raw variant because this code can
--
2.5.0
--
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next prev parent reply other threads:[~2016-01-29 19:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-29 19:42 [PATCH v3 0/3] x86/mm: INVPCID support Andy Lutomirski
2016-01-29 19:42 ` [PATCH v3 1/3] x86/mm: Add INVPCID helpers Andy Lutomirski
2016-01-29 19:42 ` [PATCH v3 2/3] x86/mm: Add a noinvpcid option to turn off INVPCID Andy Lutomirski
2016-01-29 19:42 ` Andy Lutomirski [this message]
2016-02-01 10:51 ` [PATCH v3 0/3] x86/mm: INVPCID support Borislav Petkov
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