From: Peter Zijlstra <peterz@infradead.org>
To: Alexey Klimov <alexey.klimov@linaro.org>
Cc: draszik@google.com, peter.griffin@linaro.org,
willmcvicker@google.com, mingo@kernel.org,
ulf.hansson@linaro.org, tony@atomide.com,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
axboe@kernel.dk, alim.akhtar@samsung.com,
regressions@lists.linux.dev, avri.altman@wdc.com,
bvanassche@acm.org, klimova@google.com
Subject: Re: [REGRESSION] CPUIDLE_FLAG_RCU_IDLE, blk_mq_freeze_queue_wait() and slow-stuck reboots
Date: Mon, 20 Mar 2023 10:22:36 +0100 [thread overview]
Message-ID: <20230320092236.GA2196776@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230315111606.GB2006103@hirez.programming.kicks-ass.net>
On Wed, Mar 15, 2023 at 12:16:06PM +0100, Peter Zijlstra wrote:
> So ARM has a weird 'rule' in that idle state 0 (wfi) should not have
> RCU_IDLE set, while others should have.
>
> Of the dt_init_idle_driver() users:
>
> - cpuidle-arm: arm_enter_idle_state()
> - cpuidle-big_little: bl_enter_powerdown() does ct_cpuidle_{enter,exit}()
> - cpuidle-psci: psci_enter_idle_state() uses CPU_PM_CPU_IDLE_ENTER_PARAM_RCU()
> - cpuidle-qcom-spm: spm_enter_idle_state() uses CPU_PM_CPU_IDLE_ENTER_PARAM()
> - cpuidle-riscv-sbi: sbi_cpuidle_enter_state() uses CPU_PM_CPU_IDLE_ENTER_*_PARAM()
>
> All of them start on index 1 and hence should have RCU_IDLE set, but at
> least the arm, qcom-spm and riscv-sbi don't actually appear to abide by
> the rules.
>
> Fixing that gives me the below; does that help?
FWIW.. I got the meaning of CPU_PM_CPU_IDLE_*'s _RCU thing inverted
last week; they're actually ok as is.
Specifically _RCU wants the @low_level_idle_enter to do
ct_cpuidle_{enter,exit}(). And since the ones I audited didn't in fact
do that, they should not be using the _RCU version.
next prev parent reply other threads:[~2023-03-20 9:24 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-14 23:00 [REGRESSION] CPUIDLE_FLAG_RCU_IDLE, blk_mq_freeze_queue_wait() and slow-stuck reboots Alexey Klimov
2023-03-14 23:21 ` Bart Van Assche
2023-03-17 1:38 ` Alexey Klimov
2023-03-15 11:16 ` Peter Zijlstra
2023-03-17 2:11 ` Alexey Klimov
2023-03-20 9:05 ` Peter Zijlstra
2023-03-20 9:36 ` Peter Zijlstra
2023-04-11 16:16 ` Alexey Klimov
2023-03-20 9:22 ` Peter Zijlstra [this message]
2023-03-20 13:52 ` Mark Rutland
2023-03-20 16:04 ` Mark Rutland
2023-04-02 12:40 ` Linux regression tracking #update (Thorsten Leemhuis)
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