----- On Aug 12, 2016, at 4:05 PM, Dave Watson davejwatson@xxxxxx wrote: >>>>> Would pairing one rseq_start with two rseq_finish do the trick >>>>> there ? >>>> >>>> Yes, two rseq_finish works, as long as the extra rseq management overhead >>>> is not substantial. >>> >>> I've added a commit implementing rseq_finish2() in my rseq volatile >>> dev branch. You can fetch it at: >>> >>> https://github.com/compudj/linux-percpu-dev/tree/rseq-fallback >>> >>> I also have a separate test and benchmark tree in addition to the >>> kernel selftests here: >>> >>> https://github.com/compudj/rseq-test >>> >>> I named the first write a "speculative" write, and the second write >>> the "final" write. >>> >>> Would you like to extend the test cases to cover your intended use-case ? >>> >> >>Hi Dave! >> >>I just pushed a rseq_finish2() test in my rseq-fallback branch. It implements >>a per-cpu buffer holding pointers, and pushes/pops items to/from it. >> >>To use it: >> >>cd tools/testing/selftests/rseq >>./param_test -T b >> >>(see -h for advanced usage) >> >>Let me know if I got it right! > FYI, I have started implementing rseq_finish_memcpy() and rseq_finish_memcpy_release(). The idea is to perform an inline memcpy as speculative writes before the final store (offset). I have pushed the work in progress in my dev branch. This would be an alternative to rseq_finish2() (which I still consider very useful) in cases where we want to push a sequence of bytes into a ring buffer before updating the offset counter, without having to rely on memory allocation. Feedback is welcome! Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
