Gleb Natapov wrote: > On Mon, Jul 13, 2009 at 05:49:20PM +0300, Michael S. Tsirkin wrote: > >> On Mon, Jul 13, 2009 at 05:37:50PM +0300, Gleb Natapov wrote: >> >>> On Mon, Jul 13, 2009 at 05:23:20PM +0300, Michael S. Tsirkin wrote: >>> >>>> On Mon, Jul 13, 2009 at 02:48:44PM +0300, Gleb Natapov wrote: >>>> >>>>> On Mon, Jul 13, 2009 at 02:45:51PM +0300, Michael S. Tsirkin wrote: >>>>> >>>>>> On Mon, Jul 13, 2009 at 12:12:33PM +0300, Gleb Natapov wrote: >>>>>> >>>>>>> Signed-off-by: Gleb Natapov <g...@redhat.com> >>>>>>> >>>>>> This one is probably better off left as is, >>>>>> >>>>> What do you mean "as is"? >>>>> >>>> This is a slow operation. It seems that we could use irq_lock or switch >>>> to slot lock or kvm lock here. Why do we need another one? >>>> >>>> >>> irq_lock is completely removed. So either we don't remove it and use it >>> here (and we don't need mutex so we change it to spinlock too), or we add >>> another lock with the name that actually tell us what its purpose. I prefer >>> second option. I am not sure you can use kvm lock without deadlock, and >>> slot lock? How this connected to slots management?! >>> >>> And this is not about speed of the operation. It is about making reader >>> lockless. >>> >> So, to summarize: this patch does not help speed irq injection up, the >> only reason to change locking here is cosmetical. Is this a fair >> summary? >> >> > The whole series helps to speed irq injection up. This patch is one step > towards the goal. >
FWIW: Improving the injection path in the manner Gleb is proposing will pave the way to skip the work-queue deferrment in the irqfd signal path. This is a good thing. Regards, -Greg
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