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Date:      Mon, 4 Mar 2019 00:49:07 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r344743 - head/sys/cam/ctl
Message-ID:  <201903040049.x240n7JV092136@repo.freebsd.org>
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Author: mav
Date: Mon Mar  4 00:49:07 2019
New Revision: 344743
URL: https://svnweb.freebsd.org/changeset/base/344743

Log:
  Reduce CTL threads priority to about PUSER.
  
  Since in most configurations CTL serves as network service, we found
  that this change improves local system interactivity under heavy load.
  Priority of main threads is set slightly higher then worker taskqueues
  to make them quickly sort incoming requests not creating bottlenecks,
  while plenty of worker taskqueues should be less sensitive to latency.
  
  MFC after:	1 week
  Sponsored by:	iXsystems, Inc.

Modified:
  head/sys/cam/ctl/ctl.c
  head/sys/cam/ctl/ctl_backend_block.c
  head/sys/cam/ctl/ctl_backend_ramdisk.c

Modified: head/sys/cam/ctl/ctl.c
==============================================================================
--- head/sys/cam/ctl/ctl.c	Sun Mar  3 19:55:06 2019	(r344742)
+++ head/sys/cam/ctl/ctl.c	Mon Mar  4 00:49:07 2019	(r344743)
@@ -66,6 +66,8 @@ __FBSDID("$FreeBSD$");
 #include <sys/sbuf.h>
 #include <sys/smp.h>
 #include <sys/endian.h>
+#include <sys/proc.h>
+#include <sys/sched.h>
 #include <sys/sysctl.h>
 #include <sys/nv.h>
 #include <sys/dnv.h>
@@ -13191,6 +13193,9 @@ ctl_work_thread(void *arg)
 	int retval;
 
 	CTL_DEBUG_PRINT(("ctl_work_thread starting\n"));
+	thread_lock(curthread);
+	sched_prio(curthread, PUSER - 1);
+	thread_unlock(curthread);
 
 	while (!softc->shutdown) {
 		/*
@@ -13240,7 +13245,7 @@ ctl_work_thread(void *arg)
 		}
 
 		/* Sleep until we have something to do. */
-		mtx_sleep(thr, &thr->queue_lock, PDROP | PRIBIO, "-", 0);
+		mtx_sleep(thr, &thr->queue_lock, PDROP, "-", 0);
 	}
 	thr->thread = NULL;
 	kthread_exit();
@@ -13253,6 +13258,9 @@ ctl_lun_thread(void *arg)
 	struct ctl_be_lun *be_lun;
 
 	CTL_DEBUG_PRINT(("ctl_lun_thread starting\n"));
+	thread_lock(curthread);
+	sched_prio(curthread, PUSER - 1);
+	thread_unlock(curthread);
 
 	while (!softc->shutdown) {
 		mtx_lock(&softc->ctl_lock);
@@ -13266,7 +13274,7 @@ ctl_lun_thread(void *arg)
 
 		/* Sleep until we have something to do. */
 		mtx_sleep(&softc->pending_lun_queue, &softc->ctl_lock,
-		    PDROP | PRIBIO, "-", 0);
+		    PDROP, "-", 0);
 	}
 	softc->lun_thread = NULL;
 	kthread_exit();
@@ -13284,6 +13292,9 @@ ctl_thresh_thread(void *arg)
 	int i, e, set;
 
 	CTL_DEBUG_PRINT(("ctl_thresh_thread starting\n"));
+	thread_lock(curthread);
+	sched_prio(curthread, PUSER - 1);
+	thread_unlock(curthread);
 
 	while (!softc->shutdown) {
 		mtx_lock(&softc->ctl_lock);
@@ -13371,7 +13382,7 @@ ctl_thresh_thread(void *arg)
 			}
 		}
 		mtx_sleep(&softc->thresh_thread, &softc->ctl_lock,
-		    PDROP | PRIBIO, "-", CTL_LBP_PERIOD * hz);
+		    PDROP, "-", CTL_LBP_PERIOD * hz);
 	}
 	softc->thresh_thread = NULL;
 	kthread_exit();

Modified: head/sys/cam/ctl/ctl_backend_block.c
==============================================================================
--- head/sys/cam/ctl/ctl_backend_block.c	Sun Mar  3 19:55:06 2019	(r344742)
+++ head/sys/cam/ctl/ctl_backend_block.c	Mon Mar  4 00:49:07 2019	(r344743)
@@ -2381,7 +2381,7 @@ ctl_be_block_create(struct ctl_be_block_softc *softc, 
 	 */
 	retval = taskqueue_start_threads(&be_lun->io_taskqueue,
 					 /*num threads*/num_threads,
-					 /*priority*/PWAIT,
+					 /*priority*/PUSER,
 					 /*thread name*/
 					 "%s taskq", be_lun->lunname);
 

Modified: head/sys/cam/ctl/ctl_backend_ramdisk.c
==============================================================================
--- head/sys/cam/ctl/ctl_backend_ramdisk.c	Sun Mar  3 19:55:06 2019	(r344742)
+++ head/sys/cam/ctl/ctl_backend_ramdisk.c	Mon Mar  4 00:49:07 2019	(r344743)
@@ -1149,7 +1149,7 @@ ctl_backend_ramdisk_create(struct ctl_be_ramdisk_softc
 
 	retval = taskqueue_start_threads(&be_lun->io_taskqueue,
 					 /*num threads*/1,
-					 /*priority*/PWAIT,
+					 /*priority*/PUSER,
 					 /*thread name*/
 					 "%s taskq", be_lun->lunname);
 	if (retval != 0)

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