Commit 2367e28e authored by Anna-Maria Behnsen's avatar Anna-Maria Behnsen Committed by Thomas Gleixner
Browse files

timers/migration: Spare write when nothing changed 



The wakeup value is written unconditionally in tmigr_cpu_new_timer(). When
there was no new next timer expiry that needs to be propagated, then the
value that was read before is written. This is not required.

Move the write to the place where wakeup value is changed changed.

Signed-off-by: default avatarAnna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240716-tmigr-fixes-v4-7-757baa7803fe@linutronix.de
parent 835a9a67

kernel/time/timer_migration.c

+5 −6
Original line number Diff line number Diff line
@@ -1215,14 +1215,13 @@ u64 tmigr_cpu_new_timer(u64 nextexp) 
		if (nextexp != tmc->cpuevt.nextevt.expires ||

		    tmc->cpuevt.ignore) {

			ret = tmigr_new_timer(tmc, nextexp);

		}

	}

			/*

	 * Make sure the reevaluation of timers in idle path will not miss an

	 * event.

			 * Make sure the reevaluation of timers in idle path

			 * will not miss an event.

			 */

			WRITE_ONCE(tmc->wakeup, ret);



		}

	}

	trace_tmigr_cpu_new_timer_idle(tmc, nextexp);

	raw_spin_unlock(&tmc->lock);

	return ret;