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From: Christopher Lameter <cl@linux.com>
To: "Björn Töpel" <bjorn.topel@gmail.com>
Cc: Nick Kossifidis <mick@ics.forth.gr>,
	Paul Walmsley <paul@pwsan.com>,
	Palmer Dabbelt <palmer@sifive.com>,
	linux-riscv@lists.infradead.org
Subject: Re: per-cpu thoughts
Date: Tue, 12 Mar 2019 04:22:44 +0000	[thread overview]
Message-ID: <0100016970236dfe-59c059f4-eb79-4b75-8a9b-d2738f1a3518-000000@email.amazonses.com> (raw)
In-Reply-To: <CAJ+HfNigK=FiWDtNaJm5-8QP1MEa9M+=B1PnFLGTPX5oXZRm+g@mail.gmail.com>

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On Mon, 11 Mar 2019, Björn Töpel wrote:

> >From asm-generic/percpu.h:
>
> #define this_cpu_generic_to_op(pcp, val, op)                \
> do {                                    \
>     unsigned long __flags;                        \
>     raw_local_irq_save(__flags);                    \
>     raw_cpu_generic_to_op(pcp, val, op);                \
>     raw_local_irq_restore(__flags);                    \
> } while (0)
>
> And the disassembly from my build does indeed have interrupt disabled regions.

Well there is widespread agreement here that preemption off *should be*
enough and that no counters *should be* incremented during an irqoff
session. Most per cpu counters obey that restriction and the major VM
counters are incremented in preempt off sections without disabling
interrupts.

Sorry I thought we already had that finished. Guess I jumped the gun on
that one. Ok so we have a lot more overhead to work with currently.

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  reply	other threads:[~2019-03-12  4:22 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-20 19:57 per-cpu thoughts Björn Töpel
2019-02-21 15:57 ` Christopher Lameter
2019-02-21 16:28 ` Paul Walmsley
2019-02-21 17:24   ` Björn Töpel
2019-02-21 17:49     ` Paul Walmsley
2019-02-21 19:40       ` Palmer Dabbelt
2019-02-22 15:04         ` Christopher Lameter
2019-02-22 15:36           ` Nick Kossifidis
2019-02-22 15:56             ` Christopher Lameter
2019-02-22 19:47               ` Björn Töpel
2019-02-22 19:56                 ` Christopher Lameter
2019-02-28 12:20                   ` Paul Walmsley
2019-02-28 17:58                     ` Christopher Lameter
2019-02-28 18:42                       ` Paul Walmsley
2019-02-28 19:09                         ` Christopher Lameter
2019-02-28 20:21                           ` Paul Walmsley
2019-03-01  1:13                             ` Christopher Lameter
2019-03-08  7:17                   ` Björn Töpel
2019-03-11 13:22                     ` Palmer Dabbelt
2019-03-11 14:48                       ` Björn Töpel
2019-03-11 14:56                         ` Christopher Lameter
2019-03-11 15:05                           ` Björn Töpel
2019-03-11 15:26                             ` Paul Walmsley
2019-03-11 16:48                               ` Mark Rutland
2019-03-11 18:39                                 ` Paul Walmsley
2019-03-12 11:23                                   ` Mark Rutland
2019-03-12 16:01                                     ` Paul Walmsley
2019-03-12 17:34                                       ` Christopher Lameter
2019-03-12  4:26                               ` Christopher Lameter
2019-03-12 14:21                                 ` Paul Walmsley
2019-03-12 17:42                                   ` Christopher Lameter
2019-03-12 17:59                                     ` Gary Guo
2019-03-13 18:58                                       ` Christopher Lameter
2019-03-13 20:15                                     ` Paul Walmsley
2019-03-22 14:51                               ` Nick Kossifidis
2019-03-22 17:57                                 ` Christopher Lameter
2019-03-11 15:51                             ` Christopher Lameter
2019-03-11 16:35                               ` Björn Töpel
2019-03-12  4:22                                 ` Christopher Lameter [this message]
2019-02-22 19:48             ` Björn Töpel
2019-02-22 20:53               ` Nick Kossifidis

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