From: Nadav Amit <namit@vmware.com>
To: Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Nadav Amit <namit@vmware.com>
Subject: [PATCH v4 6/9] x86/mm/tlb: Do not make is_lazy dirty for no reason
Date: Fri, 23 Aug 2019 15:41:50 -0700 [thread overview]
Message-ID: <20190823224153.15223-7-namit@vmware.com> (raw)
In-Reply-To: <20190823224153.15223-1-namit@vmware.com>
Blindly writing to is_lazy for no reason, when the written value is
identical to the old value, makes the cacheline dirty for no reason.
Avoid making such writes to prevent cache coherency traffic for no
reason.
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
arch/x86/mm/tlb.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 24c9839e3d9b..1393b3cd3697 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -322,7 +322,8 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
__flush_tlb_all();
}
#endif
- this_cpu_write(cpu_tlbstate_shared.is_lazy, false);
+ if (was_lazy)
+ this_cpu_write(cpu_tlbstate_shared.is_lazy, false);
/*
* The membarrier system call requires a full memory barrier and
--
2.17.1
next prev parent reply other threads:[~2019-08-24 6:03 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-23 22:41 [PATCH v4 0/9] x86/tlb: Concurrent TLB flushes Nadav Amit
2019-08-23 22:41 ` [PATCH v4 1/9] smp: Run functions concurrently in smp_call_function_many() Nadav Amit
2019-08-26 16:25 ` Nadav Amit
2019-08-23 22:41 ` [PATCH v4 2/9] x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote() Nadav Amit
2019-08-23 22:41 ` [PATCH v4 3/9] x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy() Nadav Amit
2019-08-23 22:41 ` [PATCH v4 4/9] x86/mm/tlb: Flush remote and local TLBs concurrently Nadav Amit
2019-08-23 22:41 ` [PATCH v4 5/9] x86/mm/tlb: Privatize cpu_tlbstate Nadav Amit
2019-08-23 22:41 ` Nadav Amit [this message]
2019-08-23 22:41 ` [PATCH v4 7/9] cpumask: Mark functions as pure Nadav Amit
2019-08-23 22:41 ` [PATCH v4 8/9] x86/mm/tlb: Remove UV special case Nadav Amit
2019-08-23 22:41 ` [PATCH v4 9/9] x86/mm/tlb: Remove unnecessary uses of the inline keyword Nadav Amit
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