On Fri, 9 Nov 2007, Andi Kleen wrote: > > > There is an interrupt enable overhead of 48 cycles that would be good to > > be able to eliminate (Kernel code usually moves counter increments into > > a neighboring interrupt disable section so that __ function can be used). > > Replace the push flags ; popf with test $IFMASK,flags ; jz 1f; sti ; 1: > That will likely make it much faster (but also bigger)
Well maybe we should change local_irq_save/restore in general? The result would be: if (!in_interrupt()) local_irq_disable() <critical section> if (!in_interrupt()) local_irq_enable(); Somehow we need to remember that we disabled interrupts. Then it get more complicated. int interrupts_disabled = 0; if (!in_interrupt()) { local_irq_disable(): interrrupts_disabled = 1; } <critical section> if (interrupts_disabled) local_irq_enable(); Not sure that this actually better. > The only problem is that there might be some code who relies on > restore_flags() restoring other flags that IF, but at least for interrupts > and local_irq_save/restore it should be fine to change. The statistics code surely does not rely on that. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/