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Date: Mon, 9 Apr 2018 23:47:48 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH v9 21/24] perf tools: Add support for the SPF perf
 event
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References: <1520963994-28477-1-git-send-email-ldufour@linux.vnet.ibm.com> <1520963994-28477-22-git-send-email-ldufour@linux.vnet.ibm.com> <alpine.DEB.2.20.1803261443560.255554@chino.kir.corp.google.com> <20180327034936.GO13724@tassilo.jf.intel.com>
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To: Andi Kleen <ak@linux.intel.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>, paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox <willy@infradead.org>, benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, hpa@zytor.com, Will Deacon <will.deacon@arm.com>, Sergey Senozhatsky <sergey.senozhatsky@gmail.com>, Andrea Arcangeli <aarcange@redhat.com>, Alexei Starovoitov <alexei.starovoitov@gmail.com>, kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com, Daniel Jordan <daniel.m.jordan@oracle.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen <tim.c.chen@linux.intel.com>, linuxppc-dev@lists.ozlabs.org, x86@kernel.org

On Mon, 26 Mar 2018, Andi Kleen wrote:

> > Aside: should there be a new spec_flt field for struct task_struct that 
> > complements maj_flt and min_flt and be exported through /proc/pid/stat?
> 
> No. task_struct is already too bloated. If you need per process tracking 
> you can always get it through trace points.
> 

Hi Andi,

We have

	count_vm_event(PGFAULT);
	count_memcg_event_mm(vma->vm_mm, PGFAULT);

in handle_mm_fault() but not counterpart for spf.  I think it would be 
helpful to be able to determine how much faulting can be done 
speculatively if there is no per-process tracking without tracing.