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[Qemu-devel] [PATCH V2 6/8] virtio-pci: use wildcard mmio eventfd for 1.
From: |
Jason Wang |
Subject: |
[Qemu-devel] [PATCH V2 6/8] virtio-pci: use wildcard mmio eventfd for 1.0 notification cap |
Date: |
Wed, 2 Sep 2015 11:25:23 +0800 |
We use data match eventfd for 1.0 notification currently. This could
be slow since software decoding is needed for mmio exit. To speed this
up, we can switch to use wild card mmio eventfd for 1.0 notification
since we can examine the queue index directly from the writing
address. KVM kernel module can utilize this by registering it to fast
mmio bus which could be as fast as pio on ept capable machine.
Lots of improvements were seen on a ept capable machine:
Guest RX:(TCP)
size/session/+throughput%/+cpu%/-+per cpu%/
64/1/+1.6807%/[-16.2421%]/[+21.3984%]/
64/2/+0.6091%/[-11.0187%]/[+13.0678%]/
64/4/+0.0553%/[-5.9768%]/[+6.4155%]/
64/8/+0.1206%/[-4.0057%]/[+4.2984%]/
256/1/-0.0031%/[-10.1166%]/[+11.2517%]/
256/2/-0.5058%/[-6.1656%]/+6.0317%]/
...
Guest TX:(TCP)
size/session/+throughput%/+cpu%/-+per cpu%/
64/1/[+18.9183%]/-0.2823%/[+19.2550%]/
64/2/[+13.5714%]/[+2.2675%]/[+11.0533%]/
64/4/[+13.1070%]/[+2.1817%]/[+10.6920%]/
64/8/[+13.0426%]/[+2.0887%]/[+10.7299%]/
256/1/[+36.2761%]/+6.3434%/[+28.1471%]/
...
1024/1/[+44.8873%]/+2.0811%/[+41.9335%]/
...
1024/4/+0.0228%/[-2.2044%]/[+2.2774%]/
...
16384/2/+0.0127%/[-5.0346%]/[+5.3148%]/
...
65535/1/[+0.0062%]/[-4.1183%]/[+4.3017%]/
65535/2/+0.0004%/[-4.2311%]/[+4.4185%]/
65535/4/+0.0107%/[-4.6106%]/[+4.8446%]/
65535/8/-0.0090%/[-5.5178%]/[+5.8306%]/
Latency:(TCP_RR)
size/session/+transaction rate%/+cpu%/-+per cpu%/
64/1/[+6.5248%]/[-9.2882%]/[+17.4322%]/
64/25/[+11.0854%]/[+0.8000%]/[+10.2038%]/
64/50/[+12.1076%]/[+2.4627%]/[+9.4131%]/
256/1/[+5.3677%]/[+10.5669%]/-4.7024%/
256/25/[+5.6402%]/-0.8962%/[+6.5955%]/
256/50/[+5.9685%]/[+1.7766%]/[+4.1188%]/
4096/1/+0.2508%/[-10.4941%]/[+12.0047%]/
4096/25/[+1.8533%]/-0.0273%/+1.8812%/
4096/50/[+1.2156%]/-1.4134%/+2.6667%/
Notes: data with '[]' is the one whose significance is greater than 95%.
Thanks Wenli Quan <address@hidden> for the benchmarking.
Cc: Michael S. Tsirkin <address@hidden>
Signed-off-by: Jason Wang <address@hidden>
---
hw/virtio/virtio-pci.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index a96890b..2d00d06 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -286,8 +286,8 @@ static int
virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
}
virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
if (modern) {
- memory_region_add_eventfd(modern_mr, modern_addr, 2,
- true, n, notifier);
+ memory_region_add_eventfd(modern_mr, modern_addr, 0,
+ false, n, notifier);
}
if (legacy) {
memory_region_add_eventfd(legacy_mr, legacy_addr, 2,
@@ -295,8 +295,8 @@ static int
virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
}
} else {
if (modern) {
- memory_region_del_eventfd(modern_mr, modern_addr, 2,
- true, n, notifier);
+ memory_region_del_eventfd(modern_mr, modern_addr, 0,
+ false, n, notifier);
}
if (legacy) {
memory_region_del_eventfd(legacy_mr, legacy_addr, 2,
--
2.1.4
- [Qemu-devel] [PATCH V2 2/8] q35: Move options common to all classes to pc_i440fx_machine_options(), (continued)
[Qemu-devel] [PATCH V2 5/8] memory: don't try to adjust endianness for zero length eventfd, Jason Wang, 2015/09/01
[Qemu-devel] [PATCH V2 6/8] virtio-pci: use wildcard mmio eventfd for 1.0 notification cap,
Jason Wang <=
[Qemu-devel] [PATCH V2 7/8] virtio-pci: introduce pio notification capability for modern device, Jason Wang, 2015/09/01
[Qemu-devel] [PATCH V2 8/8] virtio-pci: unbreak queue_enable read, Jason Wang, 2015/09/01
Re: [Qemu-devel] [PATCH V2 0/8] virtio 1.0 pci optimizations and fixes, Michael S. Tsirkin, 2015/09/10
Re: [Qemu-devel] [PATCH V2 0/8] virtio 1.0 pci optimizations and fixes, Michael S. Tsirkin, 2015/09/24