Re: [PATCH v2 00/14] perf, persistent: Kernel updates for perf tool integration

From: Peter Zijlstra <peterz@infradead.org>
To: Robert Richter <rric@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
	Arnaldo Carvalho de Melo <acme@infradead.org>,
	Jiri Olsa <jolsa@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 00/14] perf, persistent: Kernel updates for perf tool integration
Date: Mon, 24 Jun 2013 12:22:00 +0200	[thread overview]
Message-ID: <20130624102200.GR28407@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1370968960-22527-1-git-send-email-rric@kernel.org>

On Tue, Jun 11, 2013 at 06:42:26PM +0200, Robert Richter wrote:
> Note that perf tools need to support the 'attr<num>' syntax that is
> added in a separate patch set. With it we are able to run perf tool
> commands to read persistent events, e.g.:

where is this patch? I can't find it.

I also find attr<num>:<bit> a bit weird. So far we've used
<perf_event_attr::fieldname>:<bits>, so while initializing anonymous
unions is a bit difficult with 'older' GCCs and we cannot actually do:

struct perf_event_attr {
	...
	union {
		u64 flags;
		u64 disabled : 1,
		    ...
		    __reserved_1 : X;
	}
	...
};

We could fake it in userspace by allowing things like: flags:23. It
would not be a much worse hack than attr<num>:<bit> I suppose.