Peter Zijlstra <pet...@infradead.org> writes: > On Thu, Dec 19, 2013 at 09:53:44AM +0200, Alexander Shishkin wrote: >> Yes and some implementations of PT have the same issue, but you can do a >> sufficiently large high order allocation and map it to userspace and >> still no copying (or parsing/decoding) in kernel space required. > > What's sufficiently large? The largest we could possibly allocate is > something like 4k^11 which is 8M or so. That's not all that big given > you keep saying it generates in the order of 100 MB/s.
One chunk is 8M. You can have as many as the buddy allocator permits you to have. When you get a PMI, you simply switch one chunk for another and on the tracing goes. > Also, 'some implementations', that sounds like a fail right there. Why > are there already different implementations, and some which such stupid > design, of something this new? > > How about just saying NO to the ones that requires physically contiguous > allocations? No reason to leave those out, because they are still extremely useful for tracing and fit perfectly fine in a model with two buffers. Regards, -- Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
