svn commit: r355834 - head/sys/cam

[Warner Losh]

Author: imp
Date: Tue Dec 17 00:13:30 2019
New Revision: 355834
URL: https://svnweb.freebsd.org/changeset/base/355834

Log:
  Eliminate the TRIM_ACTIVE flag.
  
  Rather than a trim active flag, have a counter that can be used to
  have a absolute limit on the number of trims in flight independent of
  any I/O limiting factors.
  
  Sponsored by: Netflix

Modified:
  head/sys/cam/cam_iosched.c

Modified: head/sys/cam/cam_iosched.c
==============================================================================
--- head/sys/cam/cam_iosched.c	Tue Dec 17 00:13:26 2019	(r355833)
+++ head/sys/cam/cam_iosched.c	Tue Dec 17 00:13:30 2019	(r355834)
@@ -281,6 +281,8 @@ struct cam_iosched_softc {
 	int		trim_ticks;		/* Max ticks to hold trims */
 	int		last_trim_tick;		/* Last 'tick' time ld a trim */
 	int		queued_trims;		/* Number of trims in the queue */
+	int		max_trims;		/* Maximum number of trims pending at once */
+	int		pend_trims;		/* Number of pending trims now */
 #ifdef CAM_IOSCHED_DYNAMIC
 	int		read_bias;		/* Read bias setting */
 	int		current_read_bias;	/* Current read bias state */
@@ -707,11 +709,6 @@ cam_iosched_cl_maybe_steer(struct control_loop *clp)
 }
 #endif
 
-/*
- * Trim or similar currently pending completion. Should only be set for
- * those drivers wishing only one Trim active at a time.
- */
-#define CAM_IOSCHED_FLAG_TRIM_ACTIVE	(1ul << 0)
 			/* Callout active, and needs to be torn down */
 #define CAM_IOSCHED_FLAG_CALLOUT_ACTIVE (1ul << 1)
 
@@ -784,8 +781,7 @@ cam_iosched_has_more_trim(struct cam_iosched_softc *is
 		return false;
 	}
 
-	/* NB: Should perhaps have a max trim active independent of I/O limiters */
-	return !(isc->flags & CAM_IOSCHED_FLAG_TRIM_ACTIVE) && bp != NULL;
+	return isc->pend_trims <= isc->max_trims && bp != NULL;
 }
 
 #define cam_iosched_sort_queue(isc)	((isc)->sort_io_queue >= 0 ?	\
@@ -1109,6 +1105,7 @@ cam_iosched_init(struct cam_iosched_softc **iscp, stru
 	(*iscp)->sort_io_queue = -1;
 	bioq_init(&(*iscp)->bio_queue);
 	bioq_init(&(*iscp)->trim_queue);
+	(*iscp)->max_trims = 1;
 #ifdef CAM_IOSCHED_DYNAMIC
 	if (do_dynamic_iosched) {
 		bioq_init(&(*iscp)->write_queue);
@@ -1609,7 +1606,7 @@ void
 cam_iosched_trim_done(struct cam_iosched_softc *isc)
 {
 
-	isc->flags &= ~CAM_IOSCHED_FLAG_TRIM_ACTIVE;
+	isc->pend_trims--;
 }
 
 /*
@@ -1677,7 +1674,7 @@ void
 cam_iosched_submit_trim(struct cam_iosched_softc *isc)
 {
 
-	isc->flags |= CAM_IOSCHED_FLAG_TRIM_ACTIVE;
+	isc->pend_trims++;
 }
 
 /*
@@ -1922,8 +1919,8 @@ DB_SHOW_COMMAND(iosched, cam_iosched_db_show)
 	db_printf("Trim Q len         %d\n", biolen(&isc->trim_queue));
 	db_printf("read_bias:         %d\n", isc->read_bias);
 	db_printf("current_read_bias: %d\n", isc->current_read_bias);
-	db_printf("Trim active?       %s\n",
-	    (isc->flags & CAM_IOSCHED_FLAG_TRIM_ACTIVE) ? "yes" : "no");
+	db_printf("Trims active       %d\n", isc->pend_trim);
+	db_printf("Max trims active   %d\n", isc->max_trim);
 }
 #endif
 #endif