On Sat, 7 Dec 2019 08:43:08 -0800, Paul E. McKenney wrote: > On Sat, Dec 07, 2019 at 01:05:17PM +0900, Akira Yokosawa wrote: >> Hi Paul, >> >> This patch set fixes minor issues I noticed while reading your >> recent updates. > > Queued and pushed, along with a fix to another of my typos, thank > you very much! > >> Apart from the changes, I'd like you to mention in the answer to >> Quick Quiz 9.43 that modern Intel CPUs don't execute x86_64 >> instructions directly, but decode them into uOPs (via MOP) and >> keep them in a uOP cache [1]. >> So the execution cycle is not necessarily corresponds to instruction >> count, but heavily depends on the behavior of the microarch, which >> is not predictable without actually running the code. >> >> [1]: https://en.wikichip.org/wiki/intel/microarchitectures/skylake_(server) > > My thought is that I should review the "Hardware and it Habits" chapter, > add this information if it is not already present, and then make the > answer to this Quick Quiz refer back to that. Does that seem reasonable? Yes, it sounds quite reasonable! (Skimming through the chapter...) So Section 3.1.1 lightly touches pipelining. Section 3.2 mostly discusses memory sub-systems. Modern Intel architectures can be thought of as superscalar RISC processors which emulate x86 ISA. The transformation of x86 instructions into uOPs can be thought of as another layer of optimization (sometimes "de-optimization" from compiler writer's POV) ;-). But deep-diving this topic would cost you another chapter/appendix. I'm not sure if it's worthwhile for perfbook. Maybe it would suffice to lightly touch the difficulty of predicting execution cycles of particular instruction streams on modern microprocessors (not limited to Intel's), and put a few citations of textbooks/reference manuals. > > Also, I am thinking in terms of a release (not yet an edition) in > the near term. Anything else that absolutely must be fixed first? There remains a couple of ACCESS_ONCE()s. I'm submitting a patch to get rid of them. I don't have any other pending urgent fixes at the moment. Thanks, Akira > > Thanx, Paul > >> Thanks, Akira >> -- >> Akira Yokosawa (2): >> toyrcu: Use mathcal O for 'orders of' >> defer/rcuusage: Fix typo (that -> than) >> >> appendix/toyrcu/toyrcu.tex | 2 +- >> defer/rcuusage.tex | 2 +- >> perfbook.tex | 2 +- >> 3 files changed, 3 insertions(+), 3 deletions(-) >> >> -- >> 2.17.1 >>
