linux-kernel - Re: [PATCH v9 21/24] perf tools: Add support for the SPF perf event

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Message-Id: <de5f854b-fd39-21e1-1ce9-1c5c2d292eb8@linux.vnet.ibm.com>
Date:   Thu, 12 Apr 2018 15:44:36 +0200
From:   Laurent Dufour <ldufour@...ux.vnet.ibm.com>
To:     David Rientjes <rientjes@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>
Cc:     paulmck@...ux.vnet.ibm.com, peterz@...radead.org,
        akpm@...ux-foundation.org, kirill@...temov.name, mhocko@...nel.org,
        dave@...olabs.net, jack@...e.cz,
        Matthew Wilcox <willy@...radead.org>, benh@...nel.crashing.org,
        mpe@...erman.id.au, paulus@...ba.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
        Will Deacon <will.deacon@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        kemi.wang@...el.com, sergey.senozhatsky.work@...il.com,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        haren@...ux.vnet.ibm.com, khandual@...ux.vnet.ibm.com,
        npiggin@...il.com, bsingharora@...il.com,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: Re: [PATCH v9 21/24] perf tools: Add support for the SPF perf event

On 10/04/2018 08:47, David Rientjes wrote:
> 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.

That sounds to be a good idea, I will create a separate patch a dedicated
speculative_pgfault counter as PGFAULT is.

Thanks,
Laurent.