From a597e79ce14ea62266924acc7b8a7030a42ed29b Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Thu, 25 Aug 2011 08:26:01 +0200
Subject: block: explicit I/O accounting

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>
---
 hw/scsi-disk.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'hw/scsi-disk.c')

diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index d94b1eb53c..3cc830ff95 100644
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -57,6 +57,7 @@ typedef struct SCSIDiskReq {
     struct iovec iov;
     QEMUIOVector qiov;
     uint32_t status;
+    BlockAcctCookie acct;
 } SCSIDiskReq;
 
 struct SCSIDiskState
@@ -107,10 +108,13 @@ static void scsi_cancel_io(SCSIRequest *req)
 static void scsi_read_complete(void * opaque, int ret)
 {
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
+    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
     int n;
 
     r->req.aiocb = NULL;
 
+    bdrv_acct_done(s->bs, &r->acct);
+
     if (ret) {
         if (scsi_handle_rw_error(r, -ret, SCSI_REQ_STATUS_RETRY_READ)) {
             return;
@@ -161,6 +165,8 @@ static void scsi_read_data(SCSIRequest *req)
 
     r->iov.iov_len = n * 512;
     qemu_iovec_init_external(&r->qiov, &r->iov, 1);
+
+    bdrv_acct_start(s->bs, &r->acct, n * BDRV_SECTOR_SIZE, BDRV_ACCT_READ);
     r->req.aiocb = bdrv_aio_readv(s->bs, r->sector, &r->qiov, n,
                               scsi_read_complete, r);
     if (r->req.aiocb == NULL) {
@@ -207,11 +213,14 @@ static int scsi_handle_rw_error(SCSIDiskReq *r, int error, int type)
 static void scsi_write_complete(void * opaque, int ret)
 {
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
+    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
     uint32_t len;
     uint32_t n;
 
     r->req.aiocb = NULL;
 
+    bdrv_acct_done(s->bs, &r->acct);
+
     if (ret) {
         if (scsi_handle_rw_error(r, -ret, SCSI_REQ_STATUS_RETRY_WRITE)) {
             return;
@@ -252,6 +261,8 @@ static void scsi_write_data(SCSIRequest *req)
     n = r->iov.iov_len / 512;
     if (n) {
         qemu_iovec_init_external(&r->qiov, &r->iov, 1);
+
+        bdrv_acct_start(s->bs, &r->acct, n * BDRV_SECTOR_SIZE, BDRV_ACCT_WRITE);
         r->req.aiocb = bdrv_aio_writev(s->bs, r->sector, &r->qiov, n,
                                    scsi_write_complete, r);
         if (r->req.aiocb == NULL) {
@@ -854,13 +865,19 @@ static int scsi_disk_emulate_command(SCSIDiskReq *r, uint8_t *outbuf)
         buflen = 8;
         break;
     case SYNCHRONIZE_CACHE:
+    {
+        BlockAcctCookie acct;
+
+        bdrv_acct_start(s->bs, &acct, 0, BDRV_ACCT_FLUSH);
         ret = bdrv_flush(s->bs);
+        bdrv_acct_done(s->bs, &acct);
         if (ret < 0) {
             if (scsi_handle_rw_error(r, -ret, SCSI_REQ_STATUS_RETRY_FLUSH)) {
                 return -1;
             }
         }
         break;
+    }
     case GET_CONFIGURATION:
         memset(outbuf, 0, 8);
         /* ??? This should probably return much more information.  For now
-- 
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