Goswin, --On 30 May 2011 17:53:12 +0200 Goswin von Brederlow <[email protected]> wrote:
> But that means reading in requests from the socket. Yup > And those might just > as well be more writes to disk 1 as reads from disk 2. And reading the > request needs the memory to store writes that you don't have. That's true. At some point you need to throttle all requests. But you can respond to various degrees of memory pressure in different ways (e.g. drop read cache, write out write cache, stop acking things before they are written (a.k.a. don't expand the write cache but handle the requests synchronously), stop processing requests entirely). I am not saying you that there aren't times when you want to ACK immediately, just that it isn't always the best strategy. > Not sending ACKs > in no way garanties the client won't send more requests for a specific > disk. Of course it doesn't guarantee it. However, I think you will find it is a pretty effective feedback mechanism to slow things down. -- Alex Bligh ------------------------------------------------------------------------------ vRanger cuts backup time in half-while increasing security. With the market-leading solution for virtual backup and recovery, you get blazing-fast, flexible, and affordable data protection. Download your free trial now. http://p.sf.net/sfu/quest-d2dcopy1 _______________________________________________ Nbd-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nbd-general
