[v3,0/3] blk-mq: Don't complete in IRQ, use llist_head

Message ID	20210123201027.3262800-1-bigeasy@linutronix.de (mailing list archive)
Headers	show Return-Path: <linux-block-owner@kernel.org> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> To: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jens Axboe <axboe@kernel.dk>, Thomas Gleixner <tglx@linutronix.de>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org> Subject: [PATCH v3 0/3] blk-mq: Don't complete in IRQ, use llist_head Date: Sat, 23 Jan 2021 21:10:24 +0100 Message-Id: <20210123201027.3262800-1-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk
Series	blk-mq: Don't complete in IRQ, use llist_head \| expand [v3,0/3] blk-mq: Don't complete in IRQ, use llist_head [1/3] smp: Process pending softirqs in flush_smp_call_function_from_idle() [2/3] blk-mq: Always complete remote completions requests in softirq [3/3] blk-mq: Use llist_head for blk_cpu_done

Message ID

20210123201027.3262800-1-bigeasy@linutronix.de (mailing list archive)

Headers

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>, Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>
Subject: [PATCH v3 0/3] blk-mq: Don't complete in IRQ, use llist_head
Date: Sat, 23 Jan 2021 21:10:24 +0100
Message-Id: <20210123201027.3262800-1-bigeasy@linutronix.de>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Series

blk-mq: Don't complete in IRQ, use llist_head | expand

Message

Sebastian Andrzej Siewior Jan. 23, 2021, 8:10 p.m. UTC

Patch 2+3 were applied and then dropped by Jens due to a NOHZ+softirq
related warning [0]. Turns out a successful wakeup via
set_nr_if_polling() will not process any softirqs and the CPU may go
back to idle. This is addressed by patch #1.

smpcfd_dying_cpu() will also invoke SMP-functions calls via
flush_smp_call_function_queue() but the block layer shouldn't queue
anything because the CPU isn't online anymore.
The two caller of flush_smp_call_function_from_idle() look fine with
opening interrupts from within do_softirq().

[0] https://lkml.kernel.org/r/1ee4b31b-350e-a9f5-4349-cfb34b89829a@kernel.dk

Sebastian

Comments

Jens Axboe Jan. 25, 2021, 4:27 a.m. UTC | #1

On 1/23/21 1:10 PM, Sebastian Andrzej Siewior wrote:
> Patch 2+3 were applied and then dropped by Jens due to a NOHZ+softirq
> related warning [0]. Turns out a successful wakeup via
> set_nr_if_polling() will not process any softirqs and the CPU may go
> back to idle. This is addressed by patch #1.
> 
> smpcfd_dying_cpu() will also invoke SMP-functions calls via
> flush_smp_call_function_queue() but the block layer shouldn't queue
> anything because the CPU isn't online anymore.
> The two caller of flush_smp_call_function_from_idle() look fine with
> opening interrupts from within do_softirq().
> 
> [0] https://lkml.kernel.org/r/1ee4b31b-350e-a9f5-4349-cfb34b89829a@kernel.dk

I can queue up the block side once the IPI fix is in some stable branch
that I can pull in.

Jens Axboe Feb. 10, 2021, 2:43 p.m. UTC | #2

On 1/23/21 1:10 PM, Sebastian Andrzej Siewior wrote:
> Patch 2+3 were applied and then dropped by Jens due to a NOHZ+softirq
> related warning [0]. Turns out a successful wakeup via
> set_nr_if_polling() will not process any softirqs and the CPU may go
> back to idle. This is addressed by patch #1.
> 
> smpcfd_dying_cpu() will also invoke SMP-functions calls via
> flush_smp_call_function_queue() but the block layer shouldn't queue
> anything because the CPU isn't online anymore.
> The two caller of flush_smp_call_function_from_idle() look fine with
> opening interrupts from within do_softirq().

Applied, thanks.