linux-kernel - Re: [PATCH 02/10] x86/intel_cqm: Modify hot cpu notification handling

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Message-ID: <alpine.DEB.2.10.1506241411540.32420@vshiva-Udesk>
Date:	Wed, 24 Jun 2015 14:13:21 -0700 (PDT)
From:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>
cc:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
	linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com,
	mingo@...nel.org, tj@...nel.org, peterz@...radead.org,
	matt.fleming@...el.com, will.auld@...el.com,
	glenn.p.williamson@...el.com, kanaka.d.juvva@...el.com,
	priya.v.autee@...el.com
Subject: Re: [PATCH 02/10] x86/intel_cqm: Modify hot cpu notification
 handling



On Wed, 24 Jun 2015, Thomas Gleixner wrote:

> On Tue, 23 Jun 2015, Vikas Shivappa wrote:
>
>> This patch modifies hot cpu notification handling in Intel cache
>> monitoring:
>>
>>  - to add a new cpu to the cqm_cpumask(which has one cpu per package)
>>   during cpu start, it uses the existing package<->core map instead of
>>   looping through all cpus in cqm_cpumask.
>>  - to search for the next online sibling during cpu exit, it uses the
>>  cpumask_any_online_but instead of looping through all online cpus.  In
>>  large systems with large number of cpus the time taken to loop may be
>>  expensive and also the time increase linearly.
>
> Of course, you forgot to mention that you added the mutex around it
> and changed the hotplug logic by moving the calls to different hotplug
> events. That part wants to be a seperate patch anyway.

Will do. will send them as seperate patches.

Thanks,
Vikas
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