linux-kernel - Re: [RFC][PATCH 5/3] tracing: Add smi counting to HWLAT

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Message-ID: <81075ecf-90c3-fdb2-59eb-defd215af2eb@redhat.com>
Date:	Tue, 9 Aug 2016 15:28:57 -0300
From:	Daniel Bristot de Oliveira <bristot@...hat.com>
To:	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
	linux-rt-users@...r.kernel.org
Cc:	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Clark Williams <williams@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jon Masters <jcm@...hat.com>, Daniel Wagner <wagi@...om.org>,
	Carsten Emde <C.Emde@...dl.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [RFC][PATCH 5/3] tracing: Add smi counting to HWLAT

On 08/09/2016 03:05 PM, Steven Rostedt wrote:
> If an arch supports counting of SMIs (like newer intel chips do), then it
> can implement arch_smi_count() to return the number of SMIs that were
> triggered. The hwlat detector will call this function to get the current
> number of SMIs, and then after a period, it will read that function again,
> and if there's a difference, it will record that into the sample.
> 
> For example:
> 
>  [99] inner:13 outer:16 ts:1470352534.886878855
>  [100] inner:14 outer:18747 ts:1470352538.917966818 smi-count:2
>  [101] inner:0 outer:19162 ts:1470352539.920988709 smi-count:6
>  [102] inner:19376 outer:19276 ts:1470352540.923010578 smi-count:6
>  [103] inner:19650 outer:20665 ts:1470352541.926032469 smi-count:6
>  [104] inner:20526 outer:20680 ts:1470352542.973055312 smi-count:6
>  [105] inner:17 outer:17 ts:1470352543.990077507
> 
> Signed-off-by: Steven Rostedt <rostedt@...dmis.org>

It worked fine in a system that I can manually cause SMIs (by turning
keyboard's backlight on and off).

Tested-by: Daniel Bristot de Oliveira <bristot@...hat.com>

-- Daniel