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a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=wKuvFiaSGQ0qltdbU6+NXLB8nM8=:19 a=Ol13hO9ccFRV9qXi2t6ftBPywas=:19 a=xqWC_Br6kY4A:10 a=yJojWOMRYYMA:10 a=GoEa3M9JfhUA:10 a=7CQSdrXTAAAA:8 a=tt-1WniTR4Gn8uNbmBIA:9 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTAzMDE4MyBTYWx0ZWRfXzaAe8HdTWGcc l27CK7fUH5ysdM7GZTxhPUG2JYCC64Ne4nJfovh1/mSibO8vnQ8K8aPfDu3tdJyD8RW70Cc/L25 mDdoQL3MGdKcz2UHmxEmBGlCLpcy96LKox+TdKTHgcNflg0/TeKSgHu1RlfKic8NGuvtNmmDUWP 5/spTJ2NCpzJhMiDs0Y3bBoq+GbPlfQ45D8oZZuyyWTzzIxZ3ilAryD9WNnq90+unu15uPx7qPF qnokAnpPOKVTPKykR814s2ngF2t39S24oMzf0rro36ddAR6hYamT13CsCu/NnpofPXYTOsaDTbj Fro9zENCmUjsd8UfIkIipkudqdAGoZaYn3oJJ7C2AFj+oxHI/yAhc8bf0WzBST0ijvpmOChPEU8 oOzlomTw X-Proofpoint-GUID: _c4qjtwyQw2kcgcvBsocr0g94NcAFrUl X-Proofpoint-ORIG-GUID: _c4qjtwyQw2kcgcvBsocr0g94NcAFrUl Catalin Marinas writes: > On Tue, Sep 02, 2025 at 03:46:52PM -0700, Ankur Arora wrote: >> Catalin Marinas writes: >> > Can you have a go at poll_idle() to see how it would look like using >> > this API? It doesn't necessarily mean we have to merge them all at once >> > but it gives us a better idea of the suitability of the interface. >> >> So, I've been testing with some version of the following: >> >> diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c >> index 9b6d90a72601..361879396d0c 100644 >> --- a/drivers/cpuidle/poll_state.c >> +++ b/drivers/cpuidle/poll_state.c >> @@ -8,35 +8,25 @@ >> #include >> #include >> >> -#define POLL_IDLE_RELAX_COUNT 200 >> - >> static int __cpuidle poll_idle(struct cpuidle_device *dev, >> struct cpuidle_driver *drv, int index) >> { >> - u64 time_start; >> - >> - time_start = local_clock_noinstr(); >> + unsigned long flags; >> >> dev->poll_time_limit = false; >> >> raw_local_irq_enable(); >> if (!current_set_polling_and_test()) { >> - unsigned int loop_count = 0; >> - u64 limit; >> + u64 limit, time_end; >> >> limit = cpuidle_poll_time(drv, dev); >> + time_end = local_clock_noinstr() + limit; >> >> - while (!need_resched()) { >> - cpu_relax(); >> - if (loop_count++ < POLL_IDLE_RELAX_COUNT) >> - continue; >> + flags = smp_cond_load_relaxed_timewait(¤t_thread_info()->flags, >> + VAL & _TIF_NEED_RESCHED, >> + (local_clock_noinstr() >= time_end)); > > It makes sense to have the non-strict comparison, though it changes the > original behaviour slightly. Just mention it in the commit log. > >> >> - loop_count = 0; >> - if (local_clock_noinstr() - time_start > limit) { >> - dev->poll_time_limit = true; >> - break; >> - } >> - } >> + dev->poll_time_limit = (local_clock_noinstr() >= time_end); > > Could we do this instead and avoid another clock read: > > dev->poll_time_limit = !(flags & _TIF_NEED_RESCHED); > > In the original code, it made sense since it had to check the clock > anyway and break the loop. > > When you repost, please include the rqspinlock and poll_idle changes as > well to show how the interface is used. Sure. -- ankur