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[Qemu-devel] [RFC][PATCH] performance improvement for windows guests, ru
From: |
Vadim Rozenfeld |
Subject: |
[Qemu-devel] [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device |
Date: |
Mon, 11 Jan 2010 09:40:47 +0200 |
The following patch allows us to improve Windows virtio
block driver performance on small size requests.
Additionally, it leads to reducing of cpu usage on write IOs
repository: /home/vadimr/work/win7/qemu
branch: master
commit 68290c4e9c96f345d544ca5d2b89f27a1e67e27a
Author: Vadim Rozenfeld <address@hidden>
Date: Mon Jan 11 09:00:21 2010 +0200
[RFC][PATCH] small IOs performance for windows guests, running on top of
virtio block device
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index a2f0639..0e3a8d5 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -28,6 +28,7 @@ typedef struct VirtIOBlock
char serial_str[BLOCK_SERIAL_STRLEN + 1];
QEMUBH *bh;
size_t config_size;
+ unsigned int pending;
} VirtIOBlock;
static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
@@ -87,6 +88,8 @@ typedef struct VirtIOBlockReq
struct VirtIOBlockReq *next;
} VirtIOBlockReq;
+static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue
*vq);
+
static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
{
VirtIOBlock *s = req->dev;
@@ -95,6 +98,11 @@ static void virtio_blk_req_complete(VirtIOBlockReq
*req, int status)
virtqueue_push(s->vq, &req->elem, req->qiov.size +
sizeof(*req->in));
virtio_notify(&s->vdev, s->vq);
+ if(--s->pending == 0) {
+ virtio_queue_set_notification(s->vq, 1);
+ virtio_blk_handle_output(&s->vdev, s->vq);
+ }
+
qemu_free(req);
}
@@ -340,6 +348,9 @@ static void virtio_blk_handle_output(VirtIODevice
*vdev, VirtQueue *vq)
exit(1);
}
+ if(++s->pending == 1)
+ virtio_queue_set_notification(s->vq, 0);
+
req->out = (void *)req->elem.out_sg[0].iov_base;
req->in = (void *)req->elem.in_sg[req->elem.in_num -
1].iov_base;
- [Qemu-devel] [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device,
Vadim Rozenfeld <=
- [Qemu-devel] Re: [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device, Avi Kivity, 2010/01/11
- Message not available
- Re: [Qemu-devel] Re: [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device, Dor Laor, 2010/01/11
- Re: [Qemu-devel] Re: [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device, Christoph Hellwig, 2010/01/11
- Re: [Qemu-devel] Re: [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device, Avi Kivity, 2010/01/11
- Re: [Qemu-devel] Re: [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device, Christoph Hellwig, 2010/01/11
- Re: [Qemu-devel] Re: [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device, Christoph Hellwig, 2010/01/11
- Re: [Qemu-devel] Re: [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device, Anthony Liguori, 2010/01/11
Re: [Qemu-devel] Re: [RFC][PATCH] performance improvement for windows guests, running on top of virtio block device, Christoph Hellwig, 2010/01/11