From: Nadav Amit <nadav.amit@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Nadav Amit <namit@vmware.com>
Subject: [PATCH v5 6/8] x86/mm/tlb: Do not make is_lazy dirty for no reason
Date: Tue, 9 Feb 2021 14:16:51 -0800 [thread overview]
Message-ID: <20210209221653.614098-7-namit@vmware.com> (raw)
In-Reply-To: <20210209221653.614098-1-namit@vmware.com>
From: Nadav Amit <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 e0271e0f84ea..98d212518f67 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -469,7 +469,8 @@ 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
--
2.25.1
next prev parent reply other threads:[~2021-02-10 1:14 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-09 22:16 [PATCH v5 0/8] x86/tlb: Concurrent TLB flushes Nadav Amit
2021-02-09 22:16 ` [PATCH v5 1/8] smp: Run functions concurrently in smp_call_function_many_cond() Nadav Amit
2021-02-16 12:04 ` Peter Zijlstra
2021-02-16 18:49 ` Nadav Amit
2021-02-16 12:06 ` Peter Zijlstra
2021-02-16 16:32 ` Peter Zijlstra
2021-02-16 18:53 ` Nadav Amit
2021-02-16 18:59 ` Peter Zijlstra
2021-02-16 19:04 ` Nadav Amit
2021-02-17 1:02 ` Nadav Amit
2021-02-18 12:55 ` Peter Zijlstra
2021-02-18 8:09 ` Christoph Hellwig
2021-02-18 9:36 ` Nadav Amit
2021-02-18 11:12 ` Peter Zijlstra
2021-02-09 22:16 ` [PATCH v5 2/8] x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote() Nadav Amit
2021-02-09 22:16 ` [PATCH v5 3/8] x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy() Nadav Amit
2021-02-18 8:16 ` Christoph Hellwig
2021-02-18 8:24 ` Nadav Amit
2021-02-18 8:28 ` Christoph Hellwig
2021-02-09 22:16 ` [PATCH v5 4/8] x86/mm/tlb: Flush remote and local TLBs concurrently Nadav Amit
2021-02-16 12:10 ` Peter Zijlstra
2021-02-16 19:17 ` Nadav Amit
2021-02-18 8:14 ` Christoph Hellwig
2021-02-09 22:16 ` [PATCH v5 5/8] x86/mm/tlb: Privatize cpu_tlbstate Nadav Amit
2021-02-09 22:16 ` Nadav Amit [this message]
2021-02-09 22:16 ` [PATCH v5 7/8] cpumask: Mark functions as pure Nadav Amit
2021-02-16 12:14 ` Peter Zijlstra
2021-02-09 22:16 ` [PATCH v5 8/8] x86/mm/tlb: Remove unnecessary uses of the inline keyword Nadav Amit
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