>The conclusion is this: in Linux TCP, every N-th small packet is delayed
>by 1-2 "jiffies" (defined by the 100 Hz system clock). For Linux kernel
This 1-2 jiffies made me thing again at the PSH thing. Probably I am
completly out but could you try this patch?
Index: tcp_input.c
===================================================================
RCS file: /var/cvs/linux/net/ipv4/tcp_input.c,v
retrieving revision 1.1.2.13
diff -u -r1.1.2.13 tcp_input.c
--- tcp_input.c 1999/02/26 17:39:46 1.1.2.13
+++ linux/net/ipv4/tcp_input.c 1999/02/26 17:40:14
@@ -55,6 +55,7 @@
* work without delayed acks.
* Andi Kleen: Process packets with PSH set in the
* fast path.
+ * Andrea Arcangeli: Quickack if received a tiny PSH packet.
*/
#include <linux/config.h>
@@ -133,12 +134,8 @@
/* Tiny-grams with PSH set artifically deflate our
* ato measurement, but with a lower bound.
*/
- if(th->psh && (skb->len < (tp->mss_cache >> 1))) {
- /* Preserve the quickack state. */
- if((tp->ato & 0x7fffffff) > HZ/50)
- tp->ato = ((tp->ato & 0x80000000) |
- (HZ/50));
- }
+ if(th->psh && (skb->len < (tp->mss_cache >> 1)))
+ tcp_enter_quickack_mode(tp);
}
/* Called to compute a smoothed rtt estimate. The data fed to this
Andrea Arcangeli
-
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