From: Rik van Riel <riel@surriel.com>
To: Andy Lutomirski <luto@amacapital.net>,
Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel-team <kernel-team@fb.com>, X86 ML <x86@kernel.org>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Ingo Molnar <mingo@kernel.org>, Mike Galbraith <efault@gmx.de>,
Dave Hansen <dave.hansen@intel.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH v2 11/11] mm,sched: conditionally skip lazy TLB mm refcounting
Date: Tue, 31 Jul 2018 11:03:03 -0400 [thread overview]
Message-ID: <1533049383.28585.61.camel@surriel.com> (raw)
In-Reply-To: <C9664A02-AD53-4A6A-8A56-E729DC919E16@amacapital.net>
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On Tue, 2018-07-31 at 07:29 -0700, Andy Lutomirski wrote:
> > On Jul 31, 2018, at 2:12 AM, Peter Zijlstra <peterz@infradead.org>
> > wrote:
> >
> > > On Mon, Jul 30, 2018 at 09:05:55PM -0400, Rik van Riel wrote:
> > > > On Mon, 2018-07-30 at 18:26 +0200, Peter Zijlstra wrote:
> > > >
> > > > So for ARCH_NO_ACTIVE_MM we never touch ->active_mm and
> > > > therefore
> > > > ->active_mm == ->mm.
> > >
> > > Close, but not true for kernel threads, which have a
> > > NULL ->mm, but a non-null ->active_mm that gets passed
> > > to enter_lazy_tlb().
> >
> > I'm confused on the need for this. We mark the CPU lazy, why do we
> > still
> > care about this?
>
> I have considered renaming enter_lazy_tlb() to something like
> lazy_switch_to_kernel_mm() (or an irqs_off variant) and making it
> take no parameters or maybe just task pointer parameters.
Of all the architectures, only Alpha uses the "mm"
parameter to enter_lazy_tlb.
It uses it to store the pgd address of the current
active_mm context into the thread info of the next
task.
If it can get that from a per CPU variable, we can
get rid of the mm parameter to enter_lazy_tlb.
--
All Rights Reversed.
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next prev parent reply other threads:[~2018-07-31 15:03 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-28 21:53 [PATCH 0/10] x86,tlb,mm: more lazy TLB cleanups & optimizations Rik van Riel
2018-07-28 21:53 ` [PATCH 01/10] x86,tlb: clarify memory barrier in switch_mm_irqs_off Rik van Riel
2018-07-29 2:59 ` Andy Lutomirski
2018-07-28 21:53 ` [PATCH 02/10] smp: use __cpumask_set_cpu in on_each_cpu_cond Rik van Riel
2018-07-29 2:59 ` Andy Lutomirski
2018-07-28 21:53 ` [PATCH 03/10] smp,cpumask: introduce on_each_cpu_cond_mask Rik van Riel
2018-07-29 2:57 ` Andy Lutomirski
2018-07-29 12:00 ` Rik van Riel
[not found] ` <E710FBA5-CC5E-4941-ACBF-4AB3424F1F68@amacapital.net>
2018-07-29 17:39 ` Rik van Riel
2018-07-29 17:51 ` Rik van Riel
2018-07-29 18:55 ` Andy Lutomirski
2018-07-29 19:56 ` Linus Torvalds
2018-07-28 21:53 ` [PATCH 04/10] x86,mm: use on_each_cpu_cond for TLB flushes Rik van Riel
2018-07-29 2:58 ` Andy Lutomirski
2018-07-29 12:02 ` Rik van Riel
2018-07-28 21:53 ` [PATCH 05/10] mm,tlb: turn dummy defines into inline functions Rik van Riel
2018-07-28 21:53 ` [PATCH 06/10] mm,x86: skip cr4 and ldt reload when mm stays the same Rik van Riel
2018-07-29 4:21 ` Andy Lutomirski
2018-07-28 21:53 ` [PATCH 07/10] x86,mm: remove leave_mm cpu argument Rik van Riel
2018-07-28 21:53 ` [PATCH 08/10] arch,mm: add config variable to skip lazy TLB mm refcounting Rik van Riel
2018-07-28 21:53 ` [PATCH 09/10] mm,x86: shoot down lazy TLB references at exit_mmap time Rik van Riel
2018-07-28 21:53 ` [PATCH 10/10] mm,sched: conditionally skip lazy TLB mm refcounting Rik van Riel
2018-07-29 4:21 ` Andy Lutomirski
2018-07-29 12:11 ` Rik van Riel
2018-07-29 15:29 ` Andy Lutomirski
2018-07-29 16:55 ` Rik van Riel
2018-07-29 19:54 ` [PATCH v2 10/11] x86,tlb: really leave mm on shootdown Rik van Riel
2018-07-29 19:54 ` [PATCH v2 11/11] mm,sched: conditionally skip lazy TLB mm refcounting Rik van Riel
2018-07-30 9:55 ` Peter Zijlstra
2018-07-30 14:30 ` Rik van Riel
2018-07-30 16:26 ` Peter Zijlstra
2018-07-30 19:15 ` Rik van Riel
2018-07-30 19:30 ` Andy Lutomirski
2018-07-30 19:36 ` Rik van Riel
2018-07-30 19:49 ` Andy Lutomirski
2018-07-30 21:46 ` Rik van Riel
2018-07-30 22:00 ` Andy Lutomirski
2018-07-31 1:05 ` Rik van Riel
2018-07-31 9:12 ` Peter Zijlstra
2018-07-31 14:29 ` Andy Lutomirski
2018-07-31 15:03 ` Rik van Riel [this message]
2018-07-31 15:12 ` Peter Zijlstra
2018-07-30 11:32 ` [PATCH 0/10] x86,tlb,mm: more lazy TLB cleanups & optimizations Ingo Molnar
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