From: John Heffner <[email protected]>
Date: Thu, 1 Sep 2005 22:51:48 -0400
> I have an idea why this is going on. Packets are pre-allocated by the
> driver to be a max packet size, so when you send small packets, it
> wastes a lot of memory. Currently Linux uses the packets at the
> beginning of a connection to make a guess at how best to advertise its
> window so as not to overflow the socket's memory bounds. Since you
> start out with big segments then go to small ones, this is defeating
> that mechanism. It's actually documented in the comments in
> tcp_input.c. :)
>
> * The scheme does not work when sender sends good segments opening
> * window and then starts to feed us spagetti. But it should work
> * in common situations. Otherwise, we have to rely on queue collapsing.
That's a strong possibility, good catch John.
Although, I'm still not ruling out some box in the middle
even though I consider it less likely than your theory.
So you're suggesting that tcp_prune_queue() should do the:
if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
tcp_clamp_window(sk, tp);
check after attempting to collapse the queue.
But, that window clamping should fix the problem, as we recalculate
the window to advertise.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
| |
 |