Severe performance degradation of writev
Corinna Vinschen
corinna-cygwin@cygwin.com
Mon Jul 7 13:41:00 GMT 2014
On Jul 7 12:10, Corinna Vinschen wrote:
> On Jul 7 07:28, jojelino wrote:
> > 2008-07-27 Corinna Vinschen <corinna@vinschen.de>
> >
> > * fhandler_socket.cc (fhandler_socket::send_internal): Send never
> > more
> > then 64K bytes at once. For blocking sockets, loop until entire data
> > has been sent or an error occurs.
> > (fhandler_socket::sendto): Drop code which sends on 64K bytes.
> > (fhandler_socket::sendmsg): Ditto.
> >
> > This commit added workaround for KB823764. but it has brought another
> > performance issue when writev sends <64k of data.
>
> That's why the code contains that FIXME comment. If you have a good
> idea for simple code to split a message into the least number of pieces
> to minimize the number of WsaSendTo calls...
I took a stab at the code and I think the new version improves writing
multiple small buffers a lot. In my testing it still works in other
scenarios, too, but I would be very grateful if somebody could have a
critical look into my code changes as posted in
https://cygwin.com/ml/cygwin-cvs/2014-q3/msg00003.html
I uploaded a new developer snapshot to http://cygwin.com/snapshots/
Please give it a thorough try.
Thanks,
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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