From: Vikas Shivappa <vikas.shivappa@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>,
linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com,
mingo@kernel.org, tj@kernel.org, peterz@infradead.org,
matt.fleming@intel.com, will.auld@intel.com,
glenn.p.williamson@intel.com, kanaka.d.juvva@intel.com,
priya.v.autee@intel.com
Subject: Re: [PATCH 01/10] cpumask: Introduce cpumask_any_online_but
Date: Wed, 24 Jun 2015 14:11:48 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.10.1506241359570.32420@vshiva-Udesk> (raw)
In-Reply-To: <alpine.DEB.2.11.1506240958160.4037@nanos>
On Wed, 24 Jun 2015, Thomas Gleixner wrote:
> On Tue, 23 Jun 2015, Vikas Shivappa wrote:
>> There is currently no cpumask helper function to pick a "random" cpu
>> from a mask which is also online.
>>
>> cpumask_any_online_but() does that which is similar to cpumask_any_but()
>> but also returns a cpu that is online.
>>
>> Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
>> ---
>> include/linux/cpumask.h | 18 ++++++++++++++++++
>> 1 file changed, 18 insertions(+)
>>
>> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
>> index 27e285b..ea63b65 100644
>> --- a/include/linux/cpumask.h
>> +++ b/include/linux/cpumask.h
>> @@ -548,6 +548,24 @@ static inline void cpumask_copy(struct cpumask *dstp,
>> #define cpumask_of(cpu) (get_cpu_mask(cpu))
>>
>> /**
>> + * cpumask_any_online_but - return a "random" and online cpu in a cpumask,
>> + * but not this one
>> + * @mask: the input mask to search
>> + * @cpu: the cpu to ignore
>> + *
>> + * Returns >= nr_cpu_ids if no cpus set.
>> +*/
>> +static inline unsigned int cpumask_any_online_but(const struct cpumask *mask,
>> + unsigned int cpu)
>> +{
>> + static cpumask_t tmp;
>
> How is that supposed to work?
>
> You cannot expect, that all potential users of this function are
> magically serialized.
I am trying do something wierd with this API. trying to do
cpumask_and_any_but. But anything with 'and' operation, usually the caller
supplies the dst. Guess I can remove this API altogether and 'and' the online
and package cpu masks during hot cpu notifications.
Thanks,
Vikas
>
>> +
>> + cpumask_and(&tmp, cpu_online_mask, mask);
>> + cpumask_clear_cpu(cpu, &tmp);
>> + return cpumask_any(&tmp);
>
> Thanks,
>
> tglx
>
next prev parent reply other threads:[~2015-06-24 21:14 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-23 22:56 [PATCH V10 00/10] New cpumask API and Intel Cache Allocation support Vikas Shivappa
2015-06-23 22:56 ` [PATCH 01/10] cpumask: Introduce cpumask_any_online_but Vikas Shivappa
2015-06-24 7:59 ` Thomas Gleixner
2015-06-24 21:11 ` Vikas Shivappa [this message]
2015-06-23 22:56 ` [PATCH 02/10] x86/intel_cqm: Modify hot cpu notification handling Vikas Shivappa
2015-06-24 8:14 ` Thomas Gleixner
2015-06-24 21:13 ` Vikas Shivappa
2015-06-23 22:56 ` [PATCH 03/10] x86/intel_rapl: Modify hot cpu notification handling for RAPL Vikas Shivappa
2015-06-23 22:56 ` [PATCH 04/10] x86/intel_rdt: Cache Allocation documentation and cgroup usage guide Vikas Shivappa
2015-06-23 22:56 ` [PATCH 05/10] x86/intel_rdt: Add support for Cache Allocation detection Vikas Shivappa
2015-06-23 22:56 ` [PATCH 06/10] x86/intel_rdt: Add new cgroup and Class of service management Vikas Shivappa
2015-06-23 22:56 ` [PATCH 07/10] x86/intel_rdt: Add support for cache bit mask management Vikas Shivappa
2015-06-23 22:56 ` [PATCH 08/10] x86/intel_rdt: Implement scheduling support for Intel RDT Vikas Shivappa
2015-06-23 22:56 ` [PATCH 09/10] x86/intel_rdt: Hot cpu support for Cache Allocation Vikas Shivappa
2015-06-24 8:21 ` Thomas Gleixner
2015-06-24 21:15 ` Vikas Shivappa
2015-06-23 22:56 ` [PATCH 10/10] x86/intel_rdt: Intel haswell Cache Allocation enumeration Vikas Shivappa
-- strict thread matches above, loose matches on Subject: below --
2015-06-12 18:17 [PATCH V9 00/10] New cpumask API and Intel Cache Allocation support Vikas Shivappa
2015-06-12 18:17 ` [PATCH 01/10] cpumask: Introduce cpumask_any_online_but Vikas Shivappa
2015-06-15 12:36 ` Peter Zijlstra
2015-06-15 16:48 ` Vikas Shivappa
2015-06-16 8:20 ` Thomas Gleixner
2015-06-16 19:00 ` Vikas Shivappa
2015-06-05 0:01 [PATCH V8 00/10] New cpumask API and Intel Cache Allocation support Vikas Shivappa
2015-06-05 0:01 ` [PATCH 01/10] cpumask: Introduce cpumask_any_online_but Vikas Shivappa
2015-06-03 19:09 [PATCH V8 00/10] New cpumask API and Intel Cache Allocation support Vikas Shivappa
2015-06-03 19:09 ` [PATCH 01/10] cpumask: Introduce cpumask_any_online_but Vikas Shivappa
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