From: Shaokun Zhang <zhangshaokun@hisilicon.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Linux PM <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Guo Yang <guoyang2@huawei.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>
Subject: Re: [PATCH] cpuidle: menu: Fix long delay issue when tick stopped
Date: Thu, 27 Jan 2022 09:43:56 +0800 [thread overview]
Message-ID: <bcd3cadf-df4a-7d7a-e28a-adeb7b1a4c24@hisilicon.com> (raw)
In-Reply-To: <CAJZ5v0jBVX9H8d8g4v3W7x9MEKQpudr3NP+LGP57FioFvpq7Jg@mail.gmail.com>
Hi Rafael,
Apologies that reply later.
On 2022/1/21 2:55, Rafael J. Wysocki wrote:
> On Mon, Jan 17, 2022 at 9:16 AM Shaokun Zhang
> <zhangshaokun@hisilicon.com> wrote:
>>
...<snip>...
>> [ 37.083307] intervals = 35us
>> [ 37.083320] target_residency_ns = 10000, predicted_ns = 35482140
>> [ 37.083349] target_residency_ns = 600000, predicted_ns = 35482140
>>
>> Add idle tick wakeup judge before change predicted_ns.
>>
>> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
>> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
>> Signed-off-by: Guo Yang <guoyang2@huawei.com>
>> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
>> ---
>> drivers/cpuidle/governors/menu.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
>> index c492268..3f03843 100644
>> --- a/drivers/cpuidle/governors/menu.c
>> +++ b/drivers/cpuidle/governors/menu.c
>> @@ -313,7 +313,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
>> get_typical_interval(data, predicted_us)) *
>> NSEC_PER_USEC;
>>
>> - if (tick_nohz_tick_stopped()) {
>> + if (tick_nohz_tick_stopped() && data->tick_wakeup) {
>
> data->tick_wakeup is only true if tick_nohz_idle_got_tick() has
> returned true, but I'm not sure how this can happen after stopping the
> tick.
In order to debug this, call trace is added and as follow:
if (predicted_us < TICK_USEC)
predicted_us = ktime_to_us(delta_next);
printk("predicted_us = %uus\n", predicted_us);
dump_stack(); //add call trace print
}
When the issue came, the CPU was waken up by network interrupts
[ 1048.130033] intervals = 1us
[ 1048.130034] intervals = 1us
[ 1048.130035] intervals = 1us
[ 1048.130036] intervals = 1us
[ 1048.130037] intervals = 1us
[ 1048.130038] intervals = 1us
[ 1048.130039] intervals = 1us
[ 1048.130040] intervals = 1us
[ 1048.130041] predicted_us = 484143us
[ 1048.130043] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G OE 5.3.0-rc6 #23
[ 1048.130044] Hardware name: Huawei 2288H V5/BC11SPSCB0, BIOS 0.39 12/01/2017
[ 1048.130045] Call Trace:
[ 1048.130048] dump_stack+0x5a/0x73
[ 1048.130052] menu_select+0x3b0/0x6c0
[ 1048.130058] do_idle+0x1b4/0x290
[ 1048.130063] cpu_startup_entry+0x19/0x20
[ 1048.130067] start_secondary+0x155/0x1b0
[ 1048.130070] secondary_startup_64+0xa4/0xb0
[ 1048.130078] intervals = 1us
[ 1048.130079] intervals = 1us
[ 1048.130080] intervals = 1us
[ 1048.130081] intervals = 1us
[ 1048.130081] intervals = 1us
[ 1048.130082] intervals = 1us
[ 1048.130083] intervals = 1us
[ 1048.130084] intervals = 1us
[ 1048.130085] predicted_us = 484097us
[ 1048.130087] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G OE 5.3.0-rc6 #23
[ 1048.130088] Hardware name: Huawei 2288H V5/BC11SPSCB0, BIOS 0.39 12/01/2017
[ 1048.130089] Call Trace:
[ 1048.130093] dump_stack+0x5a/0x73
[ 1048.130097] menu_select+0x3b0/0x6c0
[ 1048.130102] do_idle+0x1b4/0x290
[ 1048.130107] cpu_startup_entry+0x19/0x20
[ 1048.130112] start_secondary+0x155/0x1b0
[ 1048.130115] secondary_startup_64+0xa4/0xb0
[ 1048.130123] intervals = 1us
[ 1048.130123] intervals = 1us
[ 1048.130124] intervals = 1us
[ 1048.130125] intervals = 1us
[ 1048.130126] intervals = 1us
[ 1048.130127] intervals = 1us
[ 1048.130128] intervals = 1us
[ 1048.130129] intervals = 1us
[ 1048.130130] predicted_us = 484053us
[ 1048.130132] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G OE 5.3.0-rc6 #23
[ 1048.130133] Hardware name: Huawei 2288H V5/BC11SPSCB0, BIOS 0.39 12/01/2017
[ 1048.130134] Call Trace:
[ 1048.130137] dump_stack+0x5a/0x73
[ 1048.130141] menu_select+0x3b0/0x6c0
[ 1048.130147] do_idle+0x1b4/0x290
[ 1048.130152] cpu_startup_entry+0x19/0x20
[ 1048.130156] start_secondary+0x155/0x1b0
[ 1048.130159] secondary_startup_64+0xa4/0xb0
>
> IOW, it looks like the change simply makes the condition be always false.
>
Agree, any good feedback is welcome and we can try it.
Thanks,
Shaokun
>> /*
>> * If the tick is already stopped, the cost of possible short
>> * idle duration misprediction is much higher, because the CPU
>> --
>> 1.8.3.1
>>
> .
>
prev parent reply other threads:[~2022-01-27 1:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-17 8:16 Shaokun Zhang
2022-01-20 18:55 ` Rafael J. Wysocki
2022-01-27 1:43 ` Shaokun Zhang [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=bcd3cadf-df4a-7d7a-e28a-adeb7b1a4c24@hisilicon.com \
--to=zhangshaokun@hisilicon.com \
--cc=daniel.lezcano@linaro.org \
--cc=guoyang2@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=rafael@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®