Messages in this thread | | | Subject | Re: [patch 1/2] x86_64 page fault NMI-safe | From | Peter Zijlstra <> | Date | Wed, 04 Aug 2010 08:27:53 +0200 |
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On Tue, 2010-08-03 at 11:56 -0700, Linus Torvalds wrote: > On Tue, Aug 3, 2010 at 10:18 AM, Peter Zijlstra <peterz@infradead.org> wrote: > > > > FWIW I really utterly detest the whole concept of sub-buffers. > > I'm not quite sure why. Is it something fundamental, or just an > implementation issue?
The sub-buffer thing that both ftrace and lttng have is creating a large buffer from a lot of small buffers, I simply don't see the point of doing that. It adds complexity and limitations for very little gain.
Their benefit is known synchronization points into the stream, you can parse each sub-buffer independently, but you can always break up a continuous stream into smaller parts or use a transport that includes index points or whatever.
Their down side is that you can never have individual events larger than the sub-buffer, you need to be aware of the sub-buffer when reserving space etc..
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