linux-kernel - Re: [Patch v2 3/3] net: Restrict receive packets queuing to housekeeping CPUs

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Message-ID: <f67187a8-be5f-ea15-77b4-165dab2b51af@redhat.com>
Date:   Tue, 23 Jun 2020 07:42:05 -0400
From:   Nitesh Narayan Lal <nitesh@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        frederic@...nel.org, mtosatti@...hat.com, juri.lelli@...hat.com,
        abelits@...vell.com, bhelgaas@...gle.com,
        linux-pci@...r.kernel.org, rostedt@...dmis.org, mingo@...nel.org,
        tglx@...utronix.de, davem@...emloft.net, akpm@...ux-foundation.org,
        sfr@...b.auug.org.au, stephen@...workplumber.org,
        rppt@...ux.vnet.ibm.com
Subject: Re: [Patch v2 3/3] net: Restrict receive packets queuing to
 housekeeping CPUs


On 6/23/20 5:23 AM, Peter Zijlstra wrote:
> On Mon, Jun 22, 2020 at 07:45:10PM -0400, Nitesh Narayan Lal wrote:
>> @@ -756,6 +757,13 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
>>  		return err;
>>  	}
>>  
>> +	hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
>> +	cpumask_and(mask, mask, housekeeping_cpumask(hk_flags));
>> +	if (cpumask_weight(mask) == 0) {
> We have cpumask_empty() for that, which is a much more efficient way of
> testing the same.

Yes, right.
I will make this change.

>
>> +		free_cpumask_var(mask);
>> +		return -EINVAL;
>> +	}
>> +
>>  	map = kzalloc(max_t(unsigned int,
>>  			    RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES),
>>  		      GFP_KERNEL);
>> -- 
>> 2.18.4
>>
-- 
Thanks
Nitesh



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