2005-09-17 14:00:20

by Tejun Heo

Subject: [QUESTION] The cost of local interrupt enable/disable

Hello, guys.

I'm curious about the cost of local_irq_enable/disable()'s on various
architectures. I found a freebsd discussion thread by googling which
says that each takes 3 cycles on i386 (very cheap), but for Pentium4,
people are talking in the order of several hundreds cycles. Are these
correct? How about other architectures?

TIA.

--
tejun

2005-09-17 14:32:19

by Anton Blanchard

Subject: Re: [QUESTION] The cost of local interrupt enable/disable

Hi,

> I'm curious about the cost of local_irq_enable/disable()'s on various
> architectures. I found a freebsd discussion thread by googling which
> says that each takes 3 cycles on i386 (very cheap), but for Pentium4,
> people are talking in the order of several hundreds cycles. Are these
> correct? How about other architectures?

It varies on ppc64, but its in the order of 10s of cycles. 40-50 cycles
is probably a decent estimation.

Anton