On Fri, 2013-07-26 at 08:28 -0400, Steven Rostedt wrote: > > My original though here was that we should be able to reserve (maximum) > > space on the per-CPU buffer, and then relinquish some of it after the > > tracepoint was written to the data, but I never had the time to check if > > that was possible to implement. It would make it a little inefficient at > > page boundaries, but that seems OK given that our maximum size is only > > ~100 bytes or so now. > Yes that would be trivial to implement. If the max buffer is ~100 bytes, > allocate 256 byte buffers per cpu. Also have a per cpu index, and then > have something like this: > > [snip] Ah, yes, that'd work. I was considering putting it into the trace event handling itself so I don't have to allocate those buffers and put the handling into every tracepoint, but I don't know how that'd work with interrupts coming in. If we assume that interrupts coming in in the middle of a tracepoint should be rare, we could do something like * allocate max buffer in on the tracing ringbuffer page * write data into it * if no interrupt came in, reduce reservation but I'm not sure how to implement step 3 :) johannes -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
