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Date:      Fri, 27 Feb 2015 21:35:36 +0000 (UTC)
From:      "Kenneth D. Merry" <ken@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r279375 - head/sys/cam
Message-ID:  <201502272135.t1RLZaHp016696@svn.freebsd.org>
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Author: ken
Date: Fri Feb 27 21:35:36 2015
New Revision: 279375
URL: https://svnweb.freebsd.org/changeset/base/279375

Log:
  Fix I/O size calculation for pass(4) driver requests and add latency
  tracking.
  
  It is important to subtract the residual from the requested
  transfer size to see how much data was actually transferred.  With
  tape drives in particular, it is common to request more data than is
  returned.
  
  Also, add I/O latency tracking for CAM requests issued by
  cam_periph_runccb().
  
  If the caller supplies a struct devstat, and the I/O is a SCSI or
  ATA I/O, we will track the elapsed time to provide I/O latency
  statistics for the request.
  
  sys/cam/scsi/cam_periph.c:
  	In cam_periph_runccb(), subtract the residual when reporting I/O
  	totals to devstat(9) for SCSI and ATA passthrough requests.
  
  	In cam_periph_runccb(), grab the I/O start time and supply
  	the start time to devstat_end_transaction() so that it can
  	calculate the elapsed I/O time.
  
  Sponsored by:	Spectra Logic
  MFC after:	1 week

Modified:
  head/sys/cam/cam_periph.c

Modified: head/sys/cam/cam_periph.c
==============================================================================
--- head/sys/cam/cam_periph.c	Fri Feb 27 21:27:02 2015	(r279374)
+++ head/sys/cam/cam_periph.c	Fri Feb 27 21:35:36 2015	(r279375)
@@ -1048,8 +1048,11 @@ cam_periph_runccb(union ccb *ccb,
 		  cam_flags camflags, u_int32_t sense_flags,
 		  struct devstat *ds)
 {
+	struct bintime *starttime;
+	struct bintime ltime;
 	int error;
  
+	starttime = NULL;
 	xpt_path_assert(ccb->ccb_h.path, MA_OWNED);
 
 	/*
@@ -1057,8 +1060,11 @@ cam_periph_runccb(union ccb *ccb,
 	 * this particular type of ccb, record the transaction start.
 	 */
 	if ((ds != NULL) && (ccb->ccb_h.func_code == XPT_SCSI_IO ||
-	    ccb->ccb_h.func_code == XPT_ATA_IO))
-		devstat_start_transaction(ds, NULL);
+	    ccb->ccb_h.func_code == XPT_ATA_IO)) {
+		starttime = &ltime;
+		binuptime(starttime);
+		devstat_start_transaction(ds, starttime);
+	}
 
 	ccb->ccb_h.cbfcnp = cam_periph_done;
 	xpt_action(ccb);
@@ -1086,22 +1092,22 @@ cam_periph_runccb(union ccb *ccb,
 	if (ds != NULL) {
 		if (ccb->ccb_h.func_code == XPT_SCSI_IO) {
 			devstat_end_transaction(ds,
-					ccb->csio.dxfer_len,
+					ccb->csio.dxfer_len - ccb->csio.resid,
 					ccb->csio.tag_action & 0x3,
 					((ccb->ccb_h.flags & CAM_DIR_MASK) ==
 					CAM_DIR_NONE) ?  DEVSTAT_NO_DATA : 
 					(ccb->ccb_h.flags & CAM_DIR_OUT) ?
 					DEVSTAT_WRITE : 
-					DEVSTAT_READ, NULL, NULL);
+					DEVSTAT_READ, NULL, starttime);
 		} else if (ccb->ccb_h.func_code == XPT_ATA_IO) {
 			devstat_end_transaction(ds,
-					ccb->ataio.dxfer_len,
+					ccb->ataio.dxfer_len - ccb->ataio.resid,
 					ccb->ataio.tag_action & 0x3,
 					((ccb->ccb_h.flags & CAM_DIR_MASK) ==
 					CAM_DIR_NONE) ?  DEVSTAT_NO_DATA : 
 					(ccb->ccb_h.flags & CAM_DIR_OUT) ?
 					DEVSTAT_WRITE : 
-					DEVSTAT_READ, NULL, NULL);
+					DEVSTAT_READ, NULL, starttime);
 		}
 	}

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