On Sun, 5 Apr 2009 10:01:06 -0700 (PDT) Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > Also, one of the issues seems to literally be that the higher-level > request handling doesn't care AT ALL about the priority. Allocating > the request itself does keep reads and writes separated, but if the > request is a SYNCIO request, and non-sync writes have filled up th > write requests, we'll have to wait for the background writes to free > up requests. > > That is quite possibly the longest wait we have in the system. it often is; latencytop tends to point that out. > > See get_request(): our default number of requests is so low that we very regularly hit the limit. In addition to setting kjournald to higher priority, I tend to set the number of requests to 4096 or so to improve interactive performance on my own systems. That way at least the elevator has a chance to see the requests ;-) -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
