Messages in this thread | | | Subject | Re: [PATCH v10 Golden] Unified trace buffer | From | Peter Zijlstra <> | Date | Tue, 30 Sep 2008 19:00:43 +0200 |
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On Tue, 2008-09-30 at 12:48 -0400, Steven Rostedt wrote: > On Tue, 30 Sep 2008, Linus Torvalds wrote: > > > > Trace buffers are different, though. Do people realize that doing the > > overloading means that you never EVER can use those buffers for anything > > else? Do people realize that it means that splice() and friends are out of > > the question? > > > > > Trouble is, looking at it I see no easy way out, > > > > Quite frankly, we could just put it at the head of the page itself. Having > > a "whole page" for the trace data is not possible anyway, since the trace > > header itself will always eat 8 bytes. > > > > And I do think it would potentially be a better model. Or at least safer. > > Actually, looking at the code, there is no reason I need to keep this in > the frame buffer itself. I've also encapsulated the accesses to the > incrementing of the pointers so it would be trivial to try other > approaches. > > The problem we had with the big array struct is that we can want large > buffers and to do that with pointers means we would need to either come up > with a large allocator or use vmap. > > But I just realized that I could also just make a link list of page > pointers and do the exact same thing without having to worry about page > frames. Again, the way I coded this up, it is quite trivial to replace > the handling of the pages with other schemes.
The list_head in the page frame should be available regardless of splice() stuffs.
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