From mboxrd@z Thu Jan  1 00:00:00 1970
From: mbligh@google.com (Martin Bligh)
Date: Thu, 9 Oct 2008 08:39:22 -0700
Subject: [ltt-dev] LTTng specialized probes
In-Reply-To: <20081009152831.GB17890@Krystal>
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	<20081006141113.GE1808@Krystal>
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	<5df78e1d0810071116i2e9790cdx8d5854dbfa50cfaf@mail.gmail.com>
	<6cc912950810071428m459aff32tb5fad99e45648170@mail.gmail.com>
	<20081008000727.GA22427@Krystal>
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Message-ID: <33307c790810090839we0b52aay60e24587efe64fe@mail.gmail.com>

> <core event header, aligned on 32 bits>
> 1-bit opt. ext. TSC (active if a 27-bits TSC overflow is detected)
> 27-bits TSC
> 4-bits event ID (ID #7 reserved to specify (optional) extended event ID,
>                 ID #6 reserved to specify both ext. event ID and event
>                 size)

That's pretty much exactly what ktrace had. You don't need to reserve
a bit for the TSC overflow, that can be an event, which gives you
31 events instead of 16 ?

However, the problem with this is you're no longer separating the
ringbuffer layer (and timing) from the event tracing layer, or at
least not on a byte boundary.