From: Nitesh Narayan Lal <nitesh@redhat.com>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
linux-pci@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
mtosatti@redhat.com, sassmann@redhat.com,
jesse.brandeburg@intel.com, lihong.yang@intel.com,
helgaas@kernel.org, jeffrey.t.kirsher@intel.com,
jacob.e.keller@intel.com, jlelli@redhat.com, hch@infradead.org,
bhelgaas@google.com, mike.marciniszyn@intel.com,
dennis.dalessandro@intel.com, thomas.lendacky@amd.com,
jerinj@marvell.com, mathias.nyman@intel.com, jiri@nvidia.com,
mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org
Subject: Re: [PATCH v2 1/4] sched/isolation: API to get housekeeping online CPUs
Date: Thu, 24 Sep 2020 08:26:18 -0400 [thread overview]
Message-ID: <ce5b0ace-518f-e17c-38dc-083fccedbc9b@redhat.com> (raw)
In-Reply-To: <20200924121150.GB19346@lenoir>
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On 9/24/20 8:11 AM, Frederic Weisbecker wrote:
> On Wed, Sep 23, 2020 at 02:11:23PM -0400, Nitesh Narayan Lal wrote:
>> Introduce a new API hk_num_online_cpus(), that can be used to
>> retrieve the number of online housekeeping CPUs that are meant to handle
>> managed IRQ jobs.
>>
>> This API is introduced for the drivers that were previously relying only
>> on num_online_cpus() to determine the number of MSIX vectors to create.
>> In an RT environment with large isolated but fewer housekeeping CPUs this
>> was leading to a situation where an attempt to move all of the vectors
>> corresponding to isolated CPUs to housekeeping CPUs were failing due to
>> per CPU vector limit.
>>
>> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com>
>> ---
>> include/linux/sched/isolation.h | 13 +++++++++++++
>> 1 file changed, 13 insertions(+)
>>
>> diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
>> index cc9f393e2a70..2e96b626e02e 100644
>> --- a/include/linux/sched/isolation.h
>> +++ b/include/linux/sched/isolation.h
>> @@ -57,4 +57,17 @@ static inline bool housekeeping_cpu(int cpu, enum hk_flags flags)
>> return true;
>> }
>>
>> +static inline unsigned int hk_num_online_cpus(void)
>> +{
>> +#ifdef CONFIG_CPU_ISOLATION
>> + const struct cpumask *hk_mask;
>> +
>> + if (static_branch_unlikely(&housekeeping_overridden)) {
>> + hk_mask = housekeeping_cpumask(HK_FLAG_MANAGED_IRQ);
> HK_FLAG_MANAGED_IRQ should be pass as an argument to the function:
>
> housekeeping_num_online_cpus(HK_FLAG_MANAGED_IRQ) because it's
> completely arbitrary otherwise.
Yeap that is more sensible, I will do that.
Do you have any other concerns/suggestions on any other patch?
>
>> + return cpumask_weight(hk_mask);
>> + }
>> +#endif
>> + return cpumask_weight(cpu_online_mask);
>> +}
>> +
>> #endif /* _LINUX_SCHED_ISOLATION_H */
>> --
>> 2.18.2
>>
--
Thanks
Nitesh
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next prev parent reply other threads:[~2020-09-24 12:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 18:11 [PATCH v2 0/4] isolation: limit msix vectors based on housekeeping CPUs Nitesh Narayan Lal
2020-09-23 18:11 ` [PATCH v2 1/4] sched/isolation: API to get housekeeping online CPUs Nitesh Narayan Lal
2020-09-24 8:40 ` peterz
2020-09-24 12:09 ` Frederic Weisbecker
2020-09-24 12:23 ` Nitesh Narayan Lal
2020-09-24 12:24 ` Peter Zijlstra
2020-09-24 12:11 ` Frederic Weisbecker
2020-09-24 12:26 ` Nitesh Narayan Lal [this message]
2020-09-24 12:46 ` Peter Zijlstra
2020-09-24 13:45 ` Nitesh Narayan Lal
2020-09-24 20:47 ` Bjorn Helgaas
2020-09-24 21:52 ` Nitesh Narayan Lal
2020-09-23 18:11 ` [PATCH v2 2/4] sched/isolation: Extend nohz_full to isolate managed IRQs Nitesh Narayan Lal
2020-09-23 18:11 ` [PATCH v2 3/4] i40e: limit msix vectors based on housekeeping CPUs Nitesh Narayan Lal
2020-09-23 18:11 ` [PATCH v2 4/4] PCI: Limit pci_alloc_irq_vectors as per " Nitesh Narayan Lal
2020-09-24 20:45 ` Bjorn Helgaas
2020-09-24 21:39 ` Nitesh Narayan Lal
2020-09-24 22:59 ` Bjorn Helgaas
2020-09-24 23:40 ` Nitesh Narayan Lal
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