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| author |   Rusty Russell <rusty@rustcorp.com.au> | 2009-06-12 22:27:02 -0600 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2009-06-12 22:27:03 +0930 |
| commit | a32a8813d0173163ba44d8f9556e0d89fdc4fb46 (patch) | |
| tree | fddb6742338047d0219e8c2536cd39b04e643b16 /drivers/lguest/hypercalls.c | |
| parent | lguest: fix race in halt code (diff) | |
| download | linux-dev-a32a8813d0173163ba44d8f9556e0d89fdc4fb46.tar.xz linux-dev-a32a8813d0173163ba44d8f9556e0d89fdc4fb46.zip | |
lguest: improve interrupt handling, speed up stream networking
lguest never checked for pending interrupts when enabling interrupts, and
things still worked. However, it makes a significant difference to TCP
performance, so it's time we fixed it by introducing a pending_irq flag
and checking it on irq_restore and irq_enable.
These two routines are now too big to patch into the 8/10 bytes
patch space, so we drop that code.
Note: The high latency on interrupt delivery had a very curious
effect: once everything else was optimized, networking without GSO was
faster than networking with GSO, since more interrupts were sent and
hence a greater chance of one getting through to the Guest!
Note2: (Almost) Closing the same loophole for iret doesn't have any
measurable effect, so I'm leaving that patch for the moment.
Before:
1GB tcpblast Guest->Host: 30.7 seconds
1GB tcpblast Guest->Host (no GSO): 76.0 seconds
After:
1GB tcpblast Guest->Host: 6.8 seconds
1GB tcpblast Guest->Host (no GSO): 27.8 seconds
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/lguest/hypercalls.c')
| -rw-r--r-- | drivers/lguest/hypercalls.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c index 54d66f05fefa..f252b71ae79e 100644 --- a/drivers/lguest/hypercalls.c +++ b/drivers/lguest/hypercalls.c @@ -37,6 +37,10 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args) /* This call does nothing, except by breaking out of the Guest * it makes us process all the asynchronous hypercalls. */ break; + case LHCALL_SEND_INTERRUPTS: + /* This call does nothing too, but by breaking out of the Guest + * it makes us process any pending interrupts. */ + break; case LHCALL_LGUEST_INIT: /* You can't get here unless you're already initialized. Don't * do that. */ |