On Tue, Aug 04, 2009 at 12:25:49PM +0300, Avi Kivity wrote: > On 08/04/2009 12:17 PM, Gleb Natapov wrote: >>> If a different read comes after the write but after our read, it will >>> have transferred the value, resulting in the same situation. >>> >>> I think reads should never block with a state based mechanism. >>> >>> >> Reader may want to poll for the status change. >> > > Without epoll(), it's inherently racy since reads from other processes > can clear the status. > This is correct for any file descriptor. Multiple readers shouldn't simultaneously read from the same files descriptor if they expect to make any sense from a result. > The "last read value" needs to be maintained for each reader, which is > not possible with read(). > Only one reader scenario is interesting. This is not some multiplexing device. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
