Hi, > 2) it's impossible to add new interfaces and we need a vectored read/write > operation to properly support a zero-copy API.
I'm eager to try vectored block ops for the xenbus block backend. > It performs at least as well as the current posix-aio code (in some > circumstances, even better). Well, I see a massive slowdown when switching from sync to aio in the xen backend code. I think the reason is that due to the lack of a vectored interface (and thus /me submitting separate aio requests for each iovec element) stuff gets parallelized *way* too much and disk seek times are killing me. > My only concern here is non-Linux Unices like FreeBSD. They have kernel > support > for posix-aio. Since we cannot extend those interfaces though, I think that > even on those platforms we should still use a thread pool. Which might change some day in the future when we manage to get iovec support into posix-aio specs. I think the interface should use qemu-prefixed function and struct names. The we can trivially map them to a system-provided aio implementation without worrying about name clashes. cheers, Gerd -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
