On Tue, Jun 09, 2009 at 02:28:01PM -0700, Giridhar Malavali wrote: > On Jun 9, 2009, at 1:40 PM, James Bottomley wrote: >> It depends what the root cause is ... if it's really latency >> introduced >> by other interrupts, then IRQF_DISABLED might be the better course. >> If >> it's purely interrupt problems in the spin locked critical sections, >> then spin_lock_irq might be the better solution ... what would be >> useful >> is to have the test rig at intel which turned up the problem see what >> happens to the results for each case. > > Earlier, I have seen that when IRQ's are shared across multiple > controllers and if the first one to register (among shared controllers) > does not disable the IRQ with IRQF_DISABLED flag,then irrespective of the > IRQ registration from other controllers, the IRQ will be enabled by > default. With this behavior and qla2xxx sharing the IRQ, just disabling > the IRQ may not be sufficient. But MSI interrupts are never shared. Also, almost every driver *should* be using IRQF_DISABLED these days (there was a proposal to eliminate IRQF_DISABLED and force every driver to explicitly re-enable interrupts if it needed them on back in March). -- 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
