linux-kernel - Re: [PATCH 5/9] x86/intel_rdt: Add new cgroup and Class of service management

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Date:	Thu, 30 Jul 2015 11:10:18 -0700 (PDT)
From:	Vikas Shivappa <vikas.shivappa@...el.com>
To:	Peter Zijlstra <peterz@...radead.org>
cc:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
	linux-kernel@...r.kernel.org, vikas.shivappa@...el.com,
	x86@...nel.org, hpa@...or.com, tglx@...utronix.de,
	mingo@...nel.org, tj@...nel.org, matt.fleming@...el.com,
	will.auld@...el.com, glenn.p.williamson@...el.com,
	kanaka.d.juvva@...el.com
Subject: Re: [PATCH 5/9] x86/intel_rdt: Add new cgroup and Class of service
 management



On Tue, 28 Jul 2015, Peter Zijlstra wrote:

> On Wed, Jul 01, 2015 at 03:21:06PM -0700, Vikas Shivappa wrote:
>>  static int __init intel_rdt_late_init(void)
>>  {
>>  	struct cpuinfo_x86 *c = &boot_cpu_data;
>> +	static struct clos_cbm_map *ccm;
>> +	u32 maxid, max_cbm_len;
>> +	size_t sizeb;
>
> Why 'sizeb' ? 'size' is still available, right?

will fix. int size should be good enough.

>
>> +	int err = 0;
>>
>> -	if (!cpu_has(c, X86_FEATURE_CAT_L3))
>> +	if (!cpu_has(c, X86_FEATURE_CAT_L3)) {
>> +		rdt_root_group.css.ss->disabled = 1;
>>  		return -ENODEV;
>> +	}
>> +	maxid = c->x86_cache_max_closid;
>> +	max_cbm_len = c->x86_cache_max_cbm_len;
>> +
>> +	sizeb = BITS_TO_LONGS(maxid) * sizeof(long);
>> +	rdtss_info.closmap = kzalloc(sizeb, GFP_KERNEL);
>> +	if (!rdtss_info.closmap) {
>> +		err = -ENOMEM;
>> +		goto out_err;
>> +	}
>> +
>> +	sizeb = maxid * sizeof(struct clos_cbm_map);
>> +	ccmap = kzalloc(sizeb, GFP_KERNEL);
>> +	if (!ccmap) {
>> +		kfree(rdtss_info.closmap);
>> +		err = -ENOMEM;
>> +		goto out_err;
>> +	}
>
> What's the expected size of max_closid? iow, how big of an array are you
> in fact allocating here?

the size of maxclosid value is 16 bits.. For systems with large CPUs this may be 
more but with EPs have only seen 20-30.
Thanks,
Vikas

>
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