aha/Documentation/lguest
Rusty Russell 4a8962e21b lguest: try to batch interrupts on network receive
Rather than triggering an interrupt every time, we only trigger an
interrupt when there are no more incoming packets (or the recv queue
is full).

However, the overhead of doing the select to figure this out is
measurable: 1M pings goes from 98 to 104 seconds, and 1G Guest->Host
TCP goes from 3.69 to 3.94 seconds.  It's close to the noise though.

I tested various timeouts, including reducing it as the number of
pending packets increased, timing a 1 gigabyte TCP send from Guest ->
Host and Host -> Guest (GSO disabled, to increase packet rate).

// time tcpblast -o -s 65536 -c 16k 192.168.2.1:9999 > /dev/null

Timeout		Guest->Host	Pkts/irq	Host->Guest	Pkts/irq
Before		11.3s		1.0		6.3s		1.0
0		11.7s		1.0		6.6s		23.5
1		17.1s		8.8		8.6s		26.0
1/pending	13.4s		1.9		6.6s		23.8
2/pending	13.6s		2.8		6.6s		24.1
5/pending	14.1s		5.0		6.6s		24.4

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:27:12 +09:30
..
.gitignore lguest: tell git to ignore Documentation/lguest/lguest 2009-04-19 23:14:02 +09:30
extract lguest: documentation I: Preparation 2007-07-26 11:35:16 -07:00
lguest.c lguest: try to batch interrupts on network receive 2009-06-12 22:27:12 +09:30
lguest.txt lguest: PAE support 2009-06-12 22:27:08 +09:30
Makefile lguest: clean up example launcher compile flags. 2009-06-12 22:27:03 +09:30