Commit-ID: 80eb865768703c0f85a0603762742ae1dedf21f0 Gitweb: https://git.kernel.org/tip/80eb865768703c0f85a0603762742ae1dedf21f0 Author: Andrea Parri <andrea.pa...@amarulasolutions.com> AuthorDate: Tue, 27 Nov 2018 12:01:10 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 11 Dec 2018 14:54:57 +0100
sched/fair: Clean up comment in nohz_idle_balance() Concerning the comment associated to the atomic_fetch_andnot() in nohz_idle_balance(), Vincent explains [1]: "[...] the comment is useless and can be removed [...] it was referring to a line code above the comment that was present in a previous iteration of the patchset. This line disappeared in final version but the comment has stayed." So remove the comment. Vincent also points out that the full ordering associated to the atomic_fetch_andnot() primitive could be relaxed, but this patch insists on the current more conservative/fully ordered solution: "Performance" isn't a concern, stay away from "correctness"/subtle relaxed (re)ordering if possible..., just make sure not to confuse the next reader with misleading/out-of-date comments. [1] http://lkml.kernel.org/r/cakftptbja-ocbrko6__npqwl3+hljzk7riccpu1r7ydo-ep...@mail.gmail.com Suggested-by: Vincent Guittot <vincent.guit...@linaro.org> Signed-off-by: Andrea Parri <andrea.pa...@amarulasolutions.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: https://lkml.kernel.org/r/20181127110110.5533-1-andrea.pa...@amarulasolutions.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/sched/fair.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ac855b2f4774..db514993565b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9533,9 +9533,7 @@ static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) return false; } - /* - * barrier, pairs with nohz_balance_enter_idle(), ensures ... - */ + /* could be _relaxed() */ flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu)); if (!(flags & NOHZ_KICK_MASK)) return false;
