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Re: [Qemu-devel] [PATCH 0/3] better I/O accounting V2
From: |
Christoph Hellwig |
Subject: |
Re: [Qemu-devel] [PATCH 0/3] better I/O accounting V2 |
Date: |
Wed, 24 Aug 2011 20:45:06 +0200 |
User-agent: |
Mutt/1.5.17 (2007-11-01) |
On Mon, Aug 22, 2011 at 11:46:00AM -0500, Ryan Harper wrote:
> So, I believe this is how it's happening.
>
> we start accounting on a write which is turned into a multiwrite via
> virtio_blk_handle_write() which calls virtio_submit_multiwrite().
>
> Then when the multiwrite completes, we invoke virtio_blk_rw_complete()
> on each part of the multiwrite. None of these requests have had their
> acct structure initialized since there was just *one* initial write.
> We could do a bdrv_acct_start() on each req, but that would break the
> concept of hiding the additional writes under the initial request.
We do initialize all write fields correctly. Where we fail right now
is for non-read/write requests. I can reproduce your issue by reading
the serial attribute in sysfs - any chance Fedora does that during boot?
The patch below should take care of these cases:
Index: qemu/hw/virtio-blk.c
===================================================================
--- qemu.orig/hw/virtio-blk.c 2011-08-24 20:32:03.764503179 +0200
+++ qemu/hw/virtio-blk.c 2011-08-24 20:35:55.716579922 +0200
@@ -59,9 +59,6 @@ static void virtio_blk_req_complete(Virt
stb_p(&req->in->status, status);
virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
virtio_notify(&s->vdev, s->vq);
-
- bdrv_acct_done(s->bs, &req->acct);
- g_free(req);
}
static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
@@ -83,6 +80,8 @@ static int virtio_blk_handle_rw_error(Vi
vm_stop(VMSTOP_DISKFULL);
} else {
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
+ bdrv_acct_done(s->bs, &req->acct);
+ g_free(req);
bdrv_mon_event(s->bs, BDRV_ACTION_REPORT, is_read);
}
@@ -102,6 +101,8 @@ static void virtio_blk_rw_complete(void
}
virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
+ bdrv_acct_done(req->dev->bs, &req->acct);
+ g_free(req);
}
static void virtio_blk_flush_complete(void *opaque, int ret)
@@ -115,6 +116,8 @@ static void virtio_blk_flush_complete(vo
}
virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
+ bdrv_acct_done(req->dev->bs, &req->acct);
+ g_free(req);
}
static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
@@ -157,6 +160,7 @@ static void virtio_blk_handle_scsi(VirtI
*/
if (req->elem.out_num < 2 || req->elem.in_num < 3) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
+ g_free(req);
return;
}
@@ -165,6 +169,7 @@ static void virtio_blk_handle_scsi(VirtI
*/
if (req->elem.out_num > 2 && req->elem.in_num > 3) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
+ g_free(req);
return;
}
@@ -231,11 +236,13 @@ static void virtio_blk_handle_scsi(VirtI
stl_p(&req->scsi->data_len, hdr.dxfer_len);
virtio_blk_req_complete(req, status);
+ g_free(req);
}
#else
static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
{
virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
+ g_free(req);
}
#endif /* __linux__ */
@@ -378,6 +385,7 @@ static void virtio_blk_handle_request(Vi
s->serial ? s->serial : "",
MIN(req->elem.in_sg[0].iov_len, VIRTIO_BLK_ID_BYTES));
virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
+ g_free(req);
} else if (type & VIRTIO_BLK_T_OUT) {
qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
req->elem.out_num - 1);
- [Qemu-devel] [PATCH 2/3] block: explicit I/O accounting, (continued)
Re: [Qemu-devel] [PATCH 0/3] better I/O accounting V2, Kevin Wolf, 2011/08/22
Re: [Qemu-devel] [PATCH 0/3] better I/O accounting V3, Christoph Hellwig, 2011/08/25
Re: [Qemu-devel] [PATCH 0/3] better I/O accounting V3, Kevin Wolf, 2011/08/25