On Wed, 9 Mar 2011 16:01:30 -0600 Steve French <smfrench@xxxxxxxxx> wrote: > > Except we don't need to wait that long with the page locked > ie for a response from the cifs server (such as Samba or Windows > or NetApp), just need to wait for it to get on the wire. > Waiting for us to get the server response would > take 10 or 100 times longer. In any case we can't resend > the same request to the server (the signature changes on the > resend since the sequence number is incremented on every > request/response so we have to recalc the checksum anyway) and > cifs requests can't get lost (as with nfs over udp). Keeping > a page locked for 10milliseconds seems like a bad idea - but > it is a little more complicated to implement (for the cifs case) > so that we end page writeback (for the non-WB_SYNC) > as quickly as reasonably possible so we don't kill perf. > The problem here is that the socket layer doesn't have a mechanism to notify us of a TCP ACK. So, we have to wait for the next-best thing -- a response from the server. -- Jeff Layton <jlayton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
