Date: Wed, 16 Aug 2017 11:19:45 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Vikas Shivappa <vikas.shivappa@linux.intel.com>
cc: vikas.shivappa@intel.com, x86@kernel.org, linux-kernel@vger.kernel.org,
        hpa@zytor.com, peterz@infradead.org, ravi.v.shankar@intel.com,
        tony.luck@intel.com, fenghua.yu@intel.com, ak@linux.intel.com,
        eranian@google.com, davidcc@google.com
Subject: Re: [PATCH 1/2] x86/intel_rdt/mbm: Fix MBM overflow handler during
 hot cpu
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References: <1502845243-20454-1-git-send-email-vikas.shivappa@linux.intel.com> <1502845243-20454-2-git-send-email-vikas.shivappa@linux.intel.com>
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On Tue, 15 Aug 2017, Vikas Shivappa wrote:
> When a CPU is dying, we cancel the worker and schedule a new worker on a
> different CPU on the same domain. But if the timer is already about to
> expire (say 0.99s) then we essentially double the interval.
> 
> We modify the hot cpu handling to cancel the delayed work on the dying
> cpu and run the worker immediately on a different cpu in same domain. We
> donot flush the worker because the MBM overflow worker reschedules the
> worker on same CPU and scans the domain->cpu_mask to get the domain
> pointer.

You could alternatively use flush and make the worker code schedule the
work on a still online CPU in the domain instead of blindly rescheduling it
on the same CPU.

Thanks,

	tglx