TCP Congestion Window Bug?

mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed

* TCP Congestion Window Bug?
@ 2001-03-04  5:39 Mark Reginald James
  2001-03-03  9:11 ` David S. Miller
  2001-03-04  6:28 ` Mark Reginald James
  0 siblings, 2 replies; 3+ messages in thread
From: Mark Reginald James @ 2001-03-04  5:39 UTC (permalink / raw)
  To: linux-kernel

Hi:

TCP only sends a packet if:

         tcp_packets_in_flight(tp) < tp->snd_cwnd

         (function tcp_snd_test in include/net/tcp.h)

but regards transmission as application-limited if

         tp->packets_out < tp->snd_cwnd

         (function tcp_cwnd_validate in include/net/tcp.h)

So the kernel _always_ thinks the connection is
application-limited, forcing many un-necessary
reductions in the size of the congestion window.

I think the condition in tcp_snd_test should be:

         tcp_packets_in_flight(tp) <= tp->snd_cwnd

Mark


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: TCP Congestion Window Bug?
  2001-03-04  5:39 TCP Congestion Window Bug? Mark Reginald James
@ 2001-03-03  9:11 ` David S. Miller
  2001-03-04  6:28 ` Mark Reginald James
  1 sibling, 0 replies; 3+ messages in thread
From: David S. Miller @ 2001-03-03  9:11 UTC (permalink / raw)
  To: Mark Reginald James; +Cc: linux-kernel


Mark Reginald James writes:
 > TCP only sends a packet if:
 > 
 >          tcp_packets_in_flight(tp) < tp->snd_cwnd
 > 
 >          (function tcp_snd_test in include/net/tcp.h)
 > 
 > but regards transmission as application-limited if
 > 
 >          tp->packets_out < tp->snd_cwnd
 > 
 >          (function tcp_cwnd_validate in include/net/tcp.h)
 > 
 > So the kernel _always_ thinks the connection is
 > application-limited

Why?  After the final "send a packet if" test, tp->packets_out will be
incremented and thus be equal to tp->snd_cwnd, marking the connection
as _not_ application limited.

Later,
David S. Miller
davem@redhat.com

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: TCP Congestion Window Bug?
  2001-03-04  5:39 TCP Congestion Window Bug? Mark Reginald James
  2001-03-03  9:11 ` David S. Miller
@ 2001-03-04  6:28 ` Mark Reginald James
  1 sibling, 0 replies; 3+ messages in thread
From: Mark Reginald James @ 2001-03-04  6:28 UTC (permalink / raw)
  To: linux-kernel

Please ignore original post.  Sorry. -- Mark





^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2001-03-03  9:27 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2001-03-04  5:39 TCP Congestion Window Bug? Mark Reginald James
2001-03-03  9:11 ` David S. Miller
2001-03-04  6:28 ` Mark Reginald James

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

all inboxes | Powered by JetHome®