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Date: Tue, 7 Nov 2017 09:14:57 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Milind Chabbi <chabbi.milind@gmail.com>
Cc: jolsa@redhat.com, Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
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        Jin Yao <yao.jin@linux.intel.com>, Kan Liang <kan.liang@intel.com>,
        Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf/core: fast breakpoint modification via
 _IOC_MODIFY_BREAKPOINT.
Message-ID: <20171107081457.GE3326@worktop>
References: <1510006156-18988-1-git-send-email-chabbi.milind@gmail.com>
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On Mon, Nov 06, 2017 at 05:09:15PM -0500, Milind Chabbi wrote:
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index 362493a..d458214 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -433,6 +433,8 @@ struct perf_event_attr {
>  #define PERF_EVENT_IOC_ID		_IOR('$', 7, __u64 *)
>  #define PERF_EVENT_IOC_SET_BPF		_IOW('$', 8, __u32)
>  #define PERF_EVENT_IOC_PAUSE_OUTPUT	_IOW('$', 9, __u32)
> +#define PERF_EVENT_IOC_MODIFY_BREAKPOINT \
> +			_IOW('$', 10, struct perf_event_attr *)


I really hate this thing. I would much rather see a more generic update
perf_event_attr interface. Where we allow modifying some of the
perf_event_attr fields.