linux-kernel - Re: [tip:perf/core] perf: Remove the nmi parameter from the swevent and overflow interface

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Message-ID: <1310146876.3282.711.camel@twins>
Date:	Fri, 08 Jul 2011 19:41:16 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Will Deacon <will.deacon@....com>
Cc:	"mingo@...hat.com" <mingo@...hat.com>,
	"dengcheng.zhu@...il.com" <dengcheng.zhu@...il.com>,
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	<linux-tip-commits@...r.kernel.org>
Subject: Re: [tip:perf/core] perf: Remove the nmi parameter from the
 swevent and overflow interface

On Fri, 2011-07-08 at 18:34 +0100, Will Deacon wrote:
> Hi Peter,
> 
> On Fri, Jul 01, 2011 at 04:21:25PM +0100, tip-bot for Peter Zijlstra wrote:
> > Commit-ID:  a8b0ca17b80e92faab46ee7179ba9e99ccb61233
> > Gitweb:     http://git.kernel.org/tip/a8b0ca17b80e92faab46ee7179ba9e99ccb61233
> > Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
> > AuthorDate: Mon, 27 Jun 2011 14:41:57 +0200
> > Committer:  Ingo Molnar <mingo@...e.hu>
> > CommitDate: Fri, 1 Jul 2011 11:06:35 +0200
> > 
> > perf: Remove the nmi parameter from the swevent and overflow interface
> > 
> > The nmi parameter indicated if we could do wakeups from the current
> > context, if not, we would set some state and self-IPI and let the
> > resulting interrupt do the wakeup.
> > 
> > For the various event classes:
> > 
> >   - hardware: nmi=0; PMI is in fact an NMI or we run irq_work_run from
> >     the PMI-tail (ARM etc.)
> >   - tracepoint: nmi=0; since tracepoint could be from NMI context.
> >   - software: nmi=[0,1]; some, like the schedule thing cannot
> >     perform wakeups, and hence need 0.
> > 
> > As one can see, there is very little nmi=1 usage, and the down-side of
> > not using it is that on some platforms some software events can have a
> > jiffy delay in wakeup (when arch_irq_work_raise isn't implemented).
> > 
> > The up-side however is that we can remove the nmi parameter and save a
> > bunch of conditionals in fast paths.
> > 
> > Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> 
> Whilst you updated the arch code in this series, you forgot to update the
> oprofile perf backend. 

Bah, I bet it skillfully hid from my grep-foo.

> I think you want something as simple as:
> 
> 
> diff --git a/drivers/oprofile/oprofile_perf.c b/drivers/oprofile/oprofile_perf.c
> index 59acf9e..94796f3 100644
> --- a/drivers/oprofile/oprofile_perf.c
> +++ b/drivers/oprofile/oprofile_perf.c
> @@ -31,7 +31,7 @@ static int num_counters;
>  /*
>   * Overflow callback for oprofile.
>   */
> -static void op_overflow_handler(struct perf_event *event, int unused,
> +static void op_overflow_handler(struct perf_event *event,
>                         struct perf_sample_data *data, struct pt_regs *regs)
>  {
>         int id;
> 

Yes, that is sufficient. Thanks!
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