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Message-ID: <4A2D6041.4050309@linux.vnet.ibm.com>
Date: Mon, 08 Jun 2009 12:02:25 -0700
From: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
To: Peter Zijlstra <peterz@...radead.org>
CC: Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf_counter: extensible perf_counter_attr
Hi Peter,
Peter Zijlstra wrote:
> Allow extending the perf_counter_attr structure by linking extended
> structures to it.
>
> Also, should we grow the directly reserved space in the structure a
> little more?
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> ---
> include/linux/perf_counter.h | 7 +++++++
> kernel/perf_counter.c | 1 +
> 2 files changed, 8 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
> index 3586df8..781d8ce 100644
> --- a/include/linux/perf_counter.h
> +++ b/include/linux/perf_counter.h
> @@ -175,6 +175,13 @@ struct perf_counter_attr {
> __u32 __reserved_3;
>
> __u64 __reserved_4;
> +
> + struct perf_counter_attr_ext *ext_attrs;
> +};
> +
> +struct perf_counter_attr_ext {
> + struct perf_counter_attr_ext *next;
> + __u64 perf_attr_ext_type;
> };
Let's say I want to extend the attributes by four 64-bit quantities... from the
above definition, I'd need four additional records chained together, right? How
about something like this instead:
struct perf_counter_attr_ext {
__u32 num_perf_attrs;
__u64 *perf_attr_ext;
};
Another alternative would be to place these two fields into perf_counter_attr
and so eliminate the extra level of indirection.
Regards,
- Corey
Corey Ashford
Software Engineer
IBM Linux Technology Center, Linux Toolchain
cjashfor@...ibm.com
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