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Fri, 10 Mar 2023 17:34:40 -0500 (EST) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-206-g57c8fdedf8-fm-20230227.001-g57c8fded Mime-Version: 1.0 Message-Id: <01a4814a-d8e3-4da2-8346-f4dc302e16f2@app.fastmail.com> In-Reply-To: <20230310150218.31510a60@gandalf.local.home> References: <20230210214645.2720847-1-shr@devkernel.io> <20230309172726.14fca32e@gandalf.local.home> <20230310150218.31510a60@gandalf.local.home> Date: Fri, 10 Mar 2023 14:34:20 -0800 From: "Stefan Roesch" To: "Steven Rostedt" Cc: kernel-team@fb.com, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: Re: [PATCH v1] mm: add tracepoints to ksm Content-Type: multipart/alternative; boundary=743a64c7b4964bb4a5e3328a72a120aa X-Rspam-User: X-Rspamd-Queue-Id: 4F51740004 X-Rspamd-Server: rspam01 X-Stat-Signature: tsrdzu7j4t8839r5qrs3mreqm667t195 X-HE-Tag: 1678487681-275621 X-HE-Meta: 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 KEuYrPyX VCYpFeS2CcQnEQla2ZglTJr9PWcP+quwhbpqklrbzPvF0RmZs85REBhOjmm3GgJec8LzUo6FAlhMZdZRawvWrAdAQXQXGlC1GjqcfRCZ2YOuUs1nabRTBKdSr6PN9BKhOmxGH3sWbcaWFo6yFYZdMBUPS7td6Rm317+MBsz/i7t5VgcoBGigXXcjGVU3YLOQdCvqA/vh2YWeRzVmgI+Ft3R982475n1U3k4ZW1x4jwY1ssBn34o522RldsPo+qfDiSxuILuDMRy17s0EBAEwrZhvcwj/D5CVLxKX3UYyAabjqm08bdWo200y5/ZP8adwig9rxQMfxSDE3ZgKMnobaneYuU+y+amHiI49R9uvsyMVhNZwhLYT4yUWfUpX2GZA1t5MmdyC7GyCv97RUS5whyqhO97FcZ/jlceiXvygM3A7r3gXunOZJJlI6c24Xv35PabcDE7uJUr6jANY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --743a64c7b4964bb4a5e3328a72a120aa Content-Type: text/plain I'll follow that approach. On Fri, Mar 10, 2023, at 12:02 PM, Steven Rostedt wrote: > On Fri, 10 Mar 2023 11:22:54 -0800 > Stefan Roesch wrote: > > > >> + trace_ksm_remove_rmap_item(stable_node->kpfn, rmap_item, rmap_item->mm); > > > > > > Instead of dereferencing the stable_node here, where the work could > > > possibly happen outside the trace event and in the hot path, could you pass > > > in the stable_node instead, and then in the TP_fast_assign() do: > > > > > > __entry->pfn = stable_node->kpfn; > > > > > > > > > > To do this, the structure would need to be exposed. Currently the > > structure is defined in ksm.c. This is an internal structure that we > > most likely don't want to expose. We can get by not printing the pfn > > and use the rmap_item to refer back to it, but exposing it directly > > here is more convenient for debugging. > > > > Any thoughts? > > Sounds like the include/trace/events/ksm.h should be local too. > > See my reply about include/trace/events/thermal.h > > https://lore.kernel.org/all/20230227100715.7d896836@gandalf.local.home/ > > And their solution. > > https://lore.kernel.org/all/20230307133735.90772-2-daniel.lezcano@linaro.org/ > > I suggest you do the same. > > -- Steve > --743a64c7b4964bb4a5e3328a72a120aa Content-Type: text/html Content-Transfer-Encoding: quoted-printable
I'll follow tha= t approach.

On Fri, Mar 10, 2023, at 12:02 PM, = Steven Rostedt wrote:
On Fri, 10 Mar 2023 11:22:54 -0800
Stefan Roesc= h <shr@devkernel.io> wrote= :

> >> + trace_ksm_remove_rmap_i= tem(stable_node->kpfn, rmap_item, rmap_item->mm);  
<= /div>
> >
> > Instead of dereferencing the= stable_node here, where the work could
> > possibly= happen outside the trace event and in the hot path, could you pass
<= /div>
> > in the stable_node instead, and then in the TP_fast_= assign() do:
> >
> > __entry-&= gt;pfn =3D stable_node->kpfn;
> >
&= gt; >  
> 
> To do t= his, the structure would need to be exposed. Currently the
> structure is defined in ksm.c. This is an internal structure that = we
> most likely don't want to expose. We can get by no= t printing the pfn
> and use the rmap_item to refer bac= k to it, but exposing it directly
> here is more conven= ient for debugging.
> 
> Any thou= ghts?

Sounds like the include/trace/events/= ksm.h should be local too.

See my reply abo= ut include/trace/events/thermal.h


And their solution.
<= /div>


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