tree 26071dbb540926c329ece0ab4d4425807021b5c8
parent 5dac051bc6030963181b69faddd9e0ad04f85fa8
author Rusty Russell <rusty@rustcorp.com.au> 1244867231 -0600
committer Rusty Russell <rusty@rustcorp.com.au> 1244811431 +0930

lguest: implement deferred interrupts in example Launcher

Rather than sending an interrupt on every buffer, we only send an interrupt
when we're about to wait for the Guest to send us a new one.  The console
input and network input still send interrupts manually, but the block device,
network and console output queues can simply rely on this logic to send
interrupts to the Guest at the right time.

The patch is cluttered by moving trigger_irq() higher in the code.

In practice, two factors make this optimization less interesting:
(1) we often only get one input at a time, even for networking,
(2) triggering an interrupt rapidly tends to get coalesced anyway.

Before:				Secs	RxIRQS	TxIRQs
 1G TCP Guest->Host:		3.72	32784	32771
 1M normal pings:		99	1000004	995541
 100,000 1k pings (-l 120):	5	49510	49058

After:
 1G TCP Guest->Host:		3.69	32809	32769
 1M normal pings:		99	1000004	996196
 100,000 1k pings (-l 120):	5	52435	52361

(Note the interrupt count on 100k pings goes *up*: see next patch).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>