On Wed, Jun 10, 2009 at 07:10:18PM +0000, James Bottomley wrote: > > That's a curious observation... I'm just trying to understand the > > numbers here, but, are we sure that this spin_lock() -> > > spin_lock_irqsave() conversion is in fact the mitigating factor. > > I think so ... the performance of both fixes is actually nearly > identical showing that the base reason (interrupt while holding hardware > spinlock adding to latency) is the correct one. > > The curiosity I had is whether we can do even better by disabling > interrupts for the whole of the ISR rather than only over the sections > where we take the hw lock, and I don't think we have conclusive evidence > either way on that. It probably doesn't matter much either way. At some point, I think Peter will be successful in forcing IRQF_DISABLED for all interrupts, and this decision will go away. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
