linux-kernel - Re: [PATCH v6 01/10] cpuidle/poll_state: poll via smp_cond_load

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Message-ID: <87bk1xs722.fsf@oracle.com>
Date: Mon, 12 Aug 2024 15:35:49 -0700
From: Ankur Arora <ankur.a.arora@...cle.com>
To: "Christoph Lameter (Ampere)" <cl@...two.org>
Cc: Ankur Arora <ankur.a.arora@...cle.com>, linux-pm@...r.kernel.org,
        kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, catalin.marinas@....com, will@...nel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        pbonzini@...hat.com, wanpengli@...cent.com, vkuznets@...hat.com,
        rafael@...nel.org, daniel.lezcano@...aro.org, peterz@...radead.org,
        arnd@...db.de, lenb@...nel.org, mark.rutland@....com,
        harisokn@...zon.com, mtosatti@...hat.com, sudeep.holla@....com,
        misono.tomohiro@...itsu.com, joao.m.martins@...cle.com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com
Subject: Re: [PATCH v6 01/10] cpuidle/poll_state: poll via
 smp_cond_load_relaxed()


Christoph Lameter (Ampere) <cl@...two.org> writes:

> On Fri, 26 Jul 2024, Ankur Arora wrote:
>
>> diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c
>> index 9b6d90a72601..532e4ed19e0f 100644
>> --- a/drivers/cpuidle/poll_state.c
>> +++ b/drivers/cpuidle/poll_state.c
>> @@ -21,21 +21,21 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev,
>>
>> 	raw_local_irq_enable();
>> 	if (!current_set_polling_and_test()) {
>> -		unsigned int loop_count = 0;
>> +		unsigned int loop_count;
>> 		u64 limit;
>
> loop_count is only used in the while loop below. So the declaration could be
> placed below the while.

That's a good idea. Will fix.

>>
>> 		limit = cpuidle_poll_time(drv, dev);
>>
>> 		while (!need_resched()) {
>> -			cpu_relax();
>> -			if (loop_count++ < POLL_IDLE_RELAX_COUNT)
>> -				continue;
>> -
>> 			loop_count = 0;
>> 			if (local_clock_noinstr() - time_start > limit) {
>> 				dev->poll_time_limit = true;
>> 				break;
>> 			}
>
> Looks ok otherwise
>
> Reviewed-by: Christoph Lameter <cl@...ux.com>

Thanks for the review.

--
ankur