Re: many outgoing tcp sockets are slower than a few

[Lennert Buytenhek <buytenh@xxxxxxxxxxxxxx>]

On Mon, Feb 21, 2005 at 06:17:16PM +0100, Christian Schmid wrote:

> >>Outgoing data. I am using sendfile() to send the file on a non-blocking 
> >>socket but the call blocks for 100 ms per socket if I get over 3000 
> >>sockets. Thats causing the massive slowdown in sum. I first thought its a 
> >>disk-issue but I tried with pure-cache data as well and it still blocks.
> >
> >O_NONBLOCK send() is really nonblocking, but O_NONBLOCK sendfile()
> >really isn't, as it still does the disk read (if any) synchronously.
> >
> >How are you making sure that you're sending "pure-cache data"?
> 
> Because thats the first I excluded. I changed the program by replacing 
> sendfile with a caching-routine plus syswrite. And it was really 
> interesting that the syswrite was the one which needs most of the 
> real-time, not the caching-routine. syswrite blocked 100 ms per socket.

'syswrite'.

Is your application written in C or perl?


--L