From: Ingo Molnar <mingo@kernel.org>
To: Rik van Riel <riel@surriel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, luto@kernel.org,
dave.hansen@intel.com, kernel-team@fb.com, efault@gmx.de,
tglx@linutronix.de, songliubraving@fb.com, hpa@zytor.com
Subject: Re: [PATCH 7/7] x86,switch_mm: skip atomic operations for init_mm
Date: Mon, 16 Jul 2018 01:04:30 +0200 [thread overview]
Message-ID: <20180715230430.GD30102@gmail.com> (raw)
In-Reply-To: <20180710142833.26231-8-riel@surriel.com>
* Rik van Riel <riel@surriel.com> wrote:
> + /*
> + * Stop remote flushes for the previous mm.
> + * Skip the idle task; we never send init_mm TLB flushing IPIs,
> + * but the bitmap manipulation can cause cache line contention.
> + */
> + if (real_prev != &init_mm) {
> + VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu,
> + mm_cpumask(real_prev)));
> + cpumask_clear_cpu(cpu, mm_cpumask(real_prev));
BTW., could this optimization be (safely) extended to all (or most) !task->mm
kernel threads?
In particular softirq and threaded irq handlers could benefit greatly I suspect in
certain networking intense workloads that happen to active them.
Thanks,
Ingo
next prev parent reply other threads:[~2018-07-15 23:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-10 14:28 [PATCH v5 0/7] x86,tlb,mm: make lazy TLB mode even lazier Rik van Riel
2018-07-10 14:28 ` [PATCH 1/7] mm: allocate mm_cpumask dynamically based on nr_cpu_ids Rik van Riel
2018-07-15 22:59 ` Ingo Molnar
2018-07-15 23:50 ` Rik van Riel
2018-07-16 1:07 ` Ingo Molnar
2018-07-10 14:28 ` [PATCH 2/7] x86,tlb: leave lazy TLB mode at page table free time Rik van Riel
2018-07-10 14:28 ` [PATCH 3/7] x86,mm: restructure switch_mm_irqs_off Rik van Riel
2018-07-10 14:28 ` [PATCH 4/7] x86,tlb: make lazy TLB mode lazier Rik van Riel
2018-07-10 14:28 ` [PATCH 5/7] x86,tlb: only send page table free TLB flush to lazy TLB CPUs Rik van Riel
2018-07-10 14:28 ` [PATCH 6/7] x86,mm: always use lazy TLB mode Rik van Riel
2018-07-10 14:28 ` [PATCH 7/7] x86,switch_mm: skip atomic operations for init_mm Rik van Riel
2018-07-15 23:04 ` Ingo Molnar [this message]
2018-07-15 23:49 ` Rik van Riel
2018-07-16 1:04 ` Ingo Molnar
2018-07-16 18:37 ` Rik van Riel
-- strict thread matches above, loose matches on Subject: below --
2018-07-16 19:03 [PATCH v6 0/7] x86,tlb,mm: make lazy TLB mode even lazier Rik van Riel
2018-07-16 19:03 ` [PATCH 7/7] x86,switch_mm: skip atomic operations for init_mm Rik van Riel
2018-07-06 21:56 [PATCH v4 0/7] x86,tlb,mm: make lazy TLB mode even lazier Rik van Riel
2018-07-06 21:56 ` [PATCH 7/7] x86,switch_mm: skip atomic operations for init_mm Rik van Riel
2018-06-29 14:29 [PATCH v3 0/7] x86,tlb,mm: make lazy TLB mode even lazier Rik van Riel
2018-06-29 14:29 ` [PATCH 7/7] x86,switch_mm: skip atomic operations for init_mm Rik van Riel
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