linux-kernel - Re: [PATCH v6] arm64: psci: Reduce the waiting time for cpu_psci_cpu

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Date:   Fri, 25 Oct 2019 16:27:37 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Yunfeng Ye <yeyunfeng@...wei.com>
Cc:     will@...nel.org, kstewart@...uxfoundation.org,
        sudeep.holla@....com, gregkh@...uxfoundation.org,
        lorenzo.pieralisi@....com, tglx@...utronix.de,
        David.Laight@...LAB.COM, mark.rutland@....com,
        linux-arm-kernel@...ts.infradead.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        hushiyuan@...wei.com, wuyun.wu@...wei.com, linfeilong@...wei.com
Subject: Re: [PATCH v6] arm64: psci: Reduce the waiting time for
 cpu_psci_cpu_kill()

On Mon, Oct 21, 2019 at 07:31:21PM +0800, Yunfeng Ye wrote:
> In cases like suspend-to-disk and suspend-to-ram, a large number of CPU
> cores need to be shut down. At present, the CPU hotplug operation is
> serialised, and the CPU cores can only be shut down one by one. In this
> process, if PSCI affinity_info() does not return LEVEL_OFF quickly,
> cpu_psci_cpu_kill() needs to wait for 10ms. If hundreds of CPU cores
> need to be shut down, it will take a long time.
> 
> Normally, there is no need to wait 10ms in cpu_psci_cpu_kill(). So
> change the wait interval from 10 ms to max 1 ms and use usleep_range()
> instead of msleep() for more accurate timer.
> 
> In addition, reducing the time interval will increase the messages
> output, so remove the "Retry ..." message, instead, track time and
> output to the the sucessful message.
> 
> Signed-off-by: Yunfeng Ye <yeyunfeng@...wei.com>
> Reviewed-by: Sudeep Holla <sudeep.holla@....com>

Queued for 5.5. Thanks.

-- 
Catalin