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Date: Fri, 24 Apr 2009 09:12:24 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
       Peter Zijlstra <peterz@infradead.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Steven Rostedt <srostedt@redhat.com>
Subject: Re: [PATCH 2/6] tracing: increase size of number of possible events
Message-ID: <20090424071224.GD24912@elte.hu>
References: <20090424043005.338878133@goodmis.org> <20090424043111.983189535@goodmis.org>
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* Steven Rostedt <rostedt@goodmis.org> wrote:

> From: Steven Rostedt <srostedt@redhat.com>
> 
> With the new event tracing registration, we must increase the number
> of events that can be registered. Currently the type field is only
> one byte, which leaves us only 256 possible events.
> 
> Since we do not save the CPU number in the tracer anymore (it is determined
> by the per cpu ring buffer that is used) we have an extra byte to use.
> 
> This patch increases the size of type from 1 byte (256 events) to
> 2 bytes (65,536 events).
> 
> It also adds a WARN_ON_ONCE if we exceed that limit.
> 
> [ Impact: allow more than 255 events ]

> -	int			type;
> +	unsigned short		type;

Hm, the changelog is not valid anymore - as here we really cut it 
down from 4 billion to 64K, right?

	Ingo