From: Jeff Garzik <jgarzik@xxxxxxxxx>
Date: Tue, 25 Mar 2008 23:14:03 -0400
David Miller wrote:From: Jeff Garzik <jgarzik@xxxxxxxxx>Replacing spin_lock() [current 8139too.c] with spin_lock_irqsave() results in a larger interrupt handler... more CPU instructions for the same result.
Date: Tue, 25 Mar 2008 22:23:24 -0400
This is bogus -- you should never need to slow down the hot path in such a way.Slow down in what way? Even on x86 saving the flags is just
about as expensive as a plain sti/cli.
Jeff, please be realistic.
These interrupt handlers about to do a PIO on a status register, which
will consume on the order of a few hundred cpu cycles.
Counting an I-cache line or two, or 18 cycles here or there,
is immaterial by comparison.