Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [PATCH] sched: Drop outdated compile-optimization comment | Date | Fri, 17 Jun 2022 12:10:05 +0100 |
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On 15/06/22 15:27, Brian Norris wrote: > Looks like this exists from way back in 2011 (commit 095c0aa83e52 > ("sched: adjust scheduler cpu power for stolen time")), when there was a > little more aggressive use of #if around these variables. That #if is > gone, and the comment just confuses the reader now. (For one, we don't > call sched_rt_avg_update() directly any more either.) >
So that sched_rt_avg_update() became update_irq_load_avg() with
91c27493e78d ("sched/irq: Add IRQ utilization tracking")
and then the #ifdef configs were reorganized in
11d4afd4ff66 ("sched/pelt: Fix warning and clean up IRQ PELT config")
I'd argue that comment is still somewhat relevant but it applies to that block:
#ifdef CONFIG_HAVE_SCHED_AVG_IRQ if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY)) update_irq_load_avg(rq, irq_delta + steal); #endif
if !CONFIG_HAVE_SCHED_AVG_IRQ then yes you'd expect the compiler to not even add a call to update_irq_load_avg() in there, but compilers aren't the most trustworthy things :-) If you feel like it, you could play with GCC/clang and see what they emit if you remove those #ifdefs.
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