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block: explicit I/O accounting

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Decouple the I/O accounting from bdrv_aio_readv/writev/flush and
make the hardware models call directly into the accounting helpers.

This means:
 - we do not count internal requests from image formats in addition
   to guest originating I/O
 - we do not double count I/O ops if the device model handles it
   chunk wise
 - we only account I/O once it actuall is done
 - can extent I/O accounting to synchronous or coroutine I/O easily
 - implement I/O latency tracking easily (see the next patch)

I've conveted the existing device model callers to the new model,
device models that are using synchronous I/O and weren't accounted
before haven't been updated yet.  Also scsi hasn't been converted
to the end-to-end accounting as I want to defer that after the pending
scsi layer overhaul.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Christoph Hellwig 2011-08-25 08:26:01 +02:00 • committed by Kevin Wolf
parent 2f4b759367
commit a597e79ce1
12 changed files with 171 additions and 50 deletions
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5
hw/xen_disk.c
View file

@ -79,6 +79,7 @@ struct ioreq {
struct XenBlkDev *blkdev;
QLIST_ENTRY(ioreq) list;
BlockAcctCookie acct;
};
struct XenBlkDev {
@ -401,6 +402,7 @@ static void qemu_aio_complete(void *opaque, int ret)
ioreq->status = ioreq->aio_errors ? BLKIF_RSP_ERROR : BLKIF_RSP_OKAY;
ioreq_unmap(ioreq);
ioreq_finish(ioreq);
bdrv_acct_done(ioreq->blkdev->bs, &ioreq->acct);
qemu_bh_schedule(ioreq->blkdev->bh);
}
@ -419,6 +421,7 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
switch (ioreq->req.operation) {
case BLKIF_OP_READ:
bdrv_acct_start(blkdev->bs, &ioreq->acct, ioreq->v.size, BDRV_ACCT_READ);
ioreq->aio_inflight++;
bdrv_aio_readv(blkdev->bs, ioreq->start / BLOCK_SIZE,
&ioreq->v, ioreq->v.size / BLOCK_SIZE,
@ -429,6 +432,8 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
if (!ioreq->req.nr_segments) {
break;
}
bdrv_acct_start(blkdev->bs, &ioreq->acct, ioreq->v.size, BDRV_ACCT_WRITE);
ioreq->aio_inflight++;
bdrv_aio_writev(blkdev->bs, ioreq->start / BLOCK_SIZE,
&ioreq->v, ioreq->v.size / BLOCK_SIZE,