On Mon, Mar 27, 2017 at 05:15:00PM +0200, Jesper Dangaard Brouer wrote: > And I also verified it worked: > > 0.63 │ mov __preempt_count,%eax > │ free_hot_cold_page(): > 1.25 │ test $0x1f0000,%eax > │ ↓ jne 1e4 > > And this simplification also made the compiler change this into a > unlikely branch, which is a micro-optimization (that I will leave up to > the compiler). Excellent! That said, I think we should define in_irq_or_nmi() in preempt.h, rather than hiding it in the memory allocator. And since we're doing that, we might as well make it look like the other definitions: diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 7eeceac52dea..af98c29abd9d 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -81,6 +81,7 @@ #define in_interrupt() (irq_count()) #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) #define in_nmi() (preempt_count() & NMI_MASK) +#define in_irq_or_nmi() (preempt_count() & (HARDIRQ_MASK | NMI_MASK)) #define in_task() (!(preempt_count() & \ (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET))) I think there are some genuine questions to be asked about the other users of in_irq() whether they really want to use in_irq_or_nmi(). There's fewer than a hundred of them, so somebody sufficiently motivated could take a look in a few days. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
