On Wed, May 04, 2011 at 01:26:02PM +0200, Goswin von Brederlow wrote: > Wouter Verhelst <[email protected]> writes: > > > On Fri, Apr 22, 2011 at 02:31:23PM +0200, folkert wrote: > >> Hi, > >> > >> I noticed something odd: > >> > >> for(;;) { > >> > >> // get timestamp in ms start > >> > >> read(fd, size_of_nbd_request) > >> > >> // get timestamp in ms end > >> > >> printf("delay: %f\n", end - start); > >> > >> // process request > >> } > >> > >> Then, on a localhost-connection with: > >> dd if=/dev/zero of=/dev/nbd0 > >> > >> in this setup I noticed that it takes 5ms for the request header to come > >> in, but only when the processing takes a while. > >> What can be the cause of this? > > > > I'm not sure. I'm aware that nbd-server performance isn't exactly > > perfect, and I plan on working on that, but it would involve some > > significant work. > > Could this be due to tcp corking? I.e. the kernel waiting for more data > to send in a single frame?
Not likely, since nbd-server doesn't set TCP_CORK. But of course it's not impossible either -- The volume of a pizza of thickness a and radius z can be described by the following formula: pi zz a ------------------------------------------------------------------------------ WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd _______________________________________________ Nbd-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nbd-general
