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 v2 6/9] x86/mm/tlb: Do not make is_lazy dirty for no reason
Date: Tue, 2 Jul 2019 16:51:48 -0700 [thread overview]
Message-ID: <20190702235151.4377-7-namit@vmware.com> (raw)
In-Reply-To: <20190702235151.4377-1-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@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 9bd24aecbd58..b47a71820f35 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:[~2019-07-03 7:14 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 23:51 [PATCH v2 0/9] x86: Concurrent TLB flushes Nadav Amit
2019-07-02 23:51 ` [PATCH v2 1/9] smp: Run functions concurrently in smp_call_function_many() Nadav Amit
2019-07-02 23:51 ` [PATCH v2 2/9] x86/mm/tlb: Remove reason as argument for flush_tlb_func_local() Nadav Amit
2019-07-02 23:51 ` [PATCH v2 3/9] x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy() Nadav Amit
2019-07-02 23:51 ` [PATCH v2 4/9] x86/mm/tlb: Flush remote and local TLBs concurrently Nadav Amit
2019-07-03 14:04 ` Juergen Gross
2019-07-03 17:02 ` Nadav Amit
2019-07-03 17:43 ` [Xen-devel] " Andrew Cooper
2019-07-03 18:09 ` Nadav Amit
2019-07-02 23:51 ` [PATCH v2 5/9] x86/mm/tlb: Privatize cpu_tlbstate Nadav Amit
2019-07-02 23:51 ` Nadav Amit [this message]
2019-07-02 23:51 ` [PATCH v2 7/9] cpumask: Mark functions as pure Nadav Amit
2019-07-02 23:51 ` [PATCH v2 8/9] x86/mm/tlb: Remove UV special case Nadav Amit
2019-07-09 19:50 ` Thomas Gleixner
2019-07-09 20:09 ` Russ Anderson
2019-07-09 20:29 ` Mike Travis
2019-07-09 21:09 ` Nadav Amit
2019-07-09 21:17 ` Mike Travis
2019-07-02 23:51 ` [PATCH v2 9/9] x86/mm/tlb: Remove unnecessary uses of the inline keyword Nadav Amit
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