On Wed, 2 Oct 2019 19:50:09 -0700, Paul E. McKenney wrote: > On Sat, Sep 28, 2019 at 10:56:10AM +0900, Akira Yokosawa wrote: >> Subject: [PATCH 0/6] ppcmem: Apply new scheme of code snippets >> >> Hi Paul, >> >> This patch series mostly consists of code snippet updates in >> formal/ppcmem.tex. >> >> Patch #1 fixes a trivial typo in dyntickrcu. >> Patch #2 is the main changes in this series. It also employs >> "cleveref" way of cross references. >> >> Patches #3--#6 touches the text and add a couples of references >> to PowerPC atomic updates in the Linux kernel. >> >> Patch #3 adds entries in bib/swtools >> Patch #4 adds citation of Git commit in 2013 >> Patches #5 and #6 add a Quick Quiz on another missing full memory >> barrier in the beginning. I'm not that sure the added Quick Quiz >> makes sense, though. If it doesn't, please skip #5 and #6. > > I believe that the additional Quick Quiz is worthwhile, but I felt > the need to edit it a bit. I have queued and pushed the result. > Could you please double-check it? As always, your edit looks perfect to me! > > And good stuff, thank you! > > Thanx, Paul > >> I remember asking you about the difference of the code emitted by >> an atomic built-in of PowerPC-GCC and the code in Linux kernel [1]. >> IIUC, the added references and Quick Quiz are related to the >> question. >> >> [1]: https://www.spinics.net/lists/perfbook/msg02077.html >> >> Seeing the history of the changes and your answer to [1], I suspect >> that now that PPC_ATOMIC_ENTRY_BARRIER is "sync", "isync" might be >> sufficient for PPC_ATOMIC_EXIT_BARRIER. Obviously I'm not an expert >> of PowerPC and can be missing something, but I couldn't help >> mentioning. Now I think I finally understand that PPC_ATOMIC_EXIT_BARRIER needs to be "sync". Semantics of __ATOMIC_SEQ_CST of GCC's atomic built-in: __ATOMIC_SEQ_CST: Enforces total ordering with all other __ATOMIC_SEQ_CST operations. OTOH, Linux kernel's value-returning atomic RMW operations need to be strongly ordered from any observer. So their semantics are different. Thanks, Akira >> >> Thanks, Akira >> -- >> Akira Yokosawa (6): >> dyntickrcu: Fix trivial typo >> ppcmem: Apply new scheme of code snippets >> bib/swtools: Add refereneces to PowerPC atomic RMW fixes >> ppcmem: Cite Git commit of PowerPC atomic_xxx_return fix >> ppcmem: Add Quick Quiz on lwsync in Listing 12.23 >> ppcmem: Move final sentence of Answer to QQZ 12.27 to the next >> >> bib/swtools.bib | 33 +++++++ >> formal/dyntickrcu.tex | 2 +- >> formal/ppcmem.tex | 210 +++++++++++++++++++++++------------------- >> 3 files changed, 149 insertions(+), 96 deletions(-) >> >> -- >> 2.17.1 >>
