svn commit: r355831 - head/sys/cam/nvme

[Warner Losh]

Author: imp
Date: Tue Dec 17 00:11:48 2019
New Revision: 355831
URL: https://svnweb.freebsd.org/changeset/base/355831

Log:
  NVME trim stuff.
  
  Add two sysctls to control pacing of nvme
  trims. kern.cam.nda.X.goal_trim is the number of upper layer
  BIO_DEELETE requests to try to collecet before sending TRIM down too
  the nvme drive. trim_ticks is the number of ticks, at mosot, to wait
  for at least goal_trim BIOS_DELEETE requests to come in.
  
  Trim pacing is useful when a large number off disjoint trims are
  comoing in from the upper layers. Since we have no way to chain
  toogether trims from the upper layers that are sent down, this acts as
  a hueristic to group trims into reasonable sized chunks. What's
  reasonable varies from drive to drive.
  
  Sponsored by: Netflix

Modified:
  head/sys/cam/nvme/nvme_da.c

Modified: head/sys/cam/nvme/nvme_da.c
==============================================================================
--- head/sys/cam/nvme/nvme_da.c	Tue Dec 17 00:10:19 2019	(r355830)
+++ head/sys/cam/nvme/nvme_da.c	Tue Dec 17 00:11:48 2019	(r355831)
@@ -177,6 +177,14 @@ static int nda_max_trim_entries = NDA_MAX_TRIM_ENTRIES
 SYSCTL_INT(_kern_cam_nda, OID_AUTO, max_trim, CTLFLAG_RDTUN,
     &nda_max_trim_entries, NDA_MAX_TRIM_ENTRIES,
     "Maximum number of BIO_DELETE to send down as a DSM TRIM.");
+static int nda_goal_trim_entries = NDA_MAX_TRIM_ENTRIES / 2;
+SYSCTL_INT(_kern_cam_nda, OID_AUTO, goal_trim, CTLFLAG_RDTUN,
+    &nda_goal_trim_entries, NDA_MAX_TRIM_ENTRIES / 2,
+    "Number of BIO_DELETE to try to accumulate before sending a DSM TRIM.");
+static int nda_trim_ticks = 50;	/* 50ms ~ 1000 Hz */
+SYSCTL_INT(_kern_cam_nda, OID_AUTO, trim_ticks, CTLFLAG_RDTUN,
+    &nda_trim_ticks, 50,
+    "Number of ticks to hold BIO_DELETEs before sending down a trim");
 
 /*
  * All NVMe media is non-rotational, so all nvme device instances
@@ -741,6 +749,9 @@ ndaregister(struct cam_periph *periph, void *arg)
 		free(softc, M_DEVBUF);
 		return(CAM_REQ_CMP_ERR);
 	}
+	/* Statically set these for the moment */
+	cam_iosched_set_trim_goal(softc->cam_iosched, nda_goal_trim_entries);
+	cam_iosched_set_trim_ticks(softc->cam_iosched, nda_trim_ticks);
 
 	/* ident_data parsing */