Re: Some interesting observations when trying to optimize vmstat handling

[Andi Kleen]

> 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) 

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.

-Andi

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