Avi Kivity wrote: > On 10/22/2009 05:14 PM, Gregory Haskins wrote: >> Yeah, I was thinking about that after I initially responded to Gleb. >> >> I am thinking something along these lines: >> >> Provide a function that lets you query a GSI for whether it supports >> LOCKLESS or not. Then we can either do one of two things: >> >> 1) Check for the LOCKLESS attribute at irqfd registration, fail if not >> present >> > > This is the most practical path and leads to the smallest code. However > it has the deficiency of exposing internal implementation details to > userspace. In theory userspace could use msi and edge-triggered > pic/ioapic interrupts equally well, it shouldn't have to know that we > didn't bother to lockfree ioapic/pic. > >> 2) Cache the LOCKLESS attribute in the irqfd structure, and either go >> direct or defer to a workqueue depending on the flag. >> > > While this leads to larger code, it is more consistent. > Yeah, I think you are right. Consider these two patches retracted, and I will rewrite it with this concept in place. Kind Regards, -Greg
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