[src/trunk]: src/sys/kern Expose the worker thread idle timeout via sysctl as...

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d9d66aa2472a
branches:  trunk
changeset: 995596:d9d66aa2472a
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Sat Dec 29 04:39:14 2018 +0000

description:
Expose the worker thread idle timeout via sysctl as "kern.threadpool.idle_ms".

diffstat:

 sys/kern/kern_threadpool.c |  58 ++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 53 insertions(+), 5 deletions(-)

diffs (100 lines):

diff -r b6e20e8b4070 -r d9d66aa2472a sys/kern/kern_threadpool.c
--- a/sys/kern/kern_threadpool.c        Sat Dec 29 04:05:47 2018 +0000
+++ b/sys/kern/kern_threadpool.c        Sat Dec 29 04:39:14 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_threadpool.c,v 1.13 2018/12/28 00:15:57 thorpej Exp $     */
+/*     $NetBSD: kern_threadpool.c,v 1.14 2018/12/29 04:39:14 thorpej Exp $     */
 
 /*-
  * Copyright (c) 2014, 2018 The NetBSD Foundation, Inc.
@@ -81,7 +81,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_threadpool.c,v 1.13 2018/12/28 00:15:57 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_threadpool.c,v 1.14 2018/12/29 04:39:14 thorpej Exp $");
 
 #include <sys/types.h>
 #include <sys/param.h>
@@ -98,6 +98,7 @@
 #include <sys/proc.h>
 #include <sys/queue.h>
 #include <sys/systm.h>
+#include <sys/sysctl.h>
 #include <sys/threadpool.h>
 
 /* Data structures */
@@ -144,8 +145,8 @@
 
 static kmutex_t                threadpools_lock __cacheline_aligned;
 
-       /* Idle out threads after 30 seconds */
-#define        THREADPOOL_IDLE_TICKS   mstohz(30 * 1000)
+       /* Default to 30 second idle timeout for pool threads. */
+static int     threadpool_idle_time_ms = 30 * 1000;
 
 struct threadpool_unbound {
        struct threadpool               tpu_pool;
@@ -226,6 +227,53 @@
 #define        TP_LOG(x)               /* nothing */
 #endif /* THREADPOOL_VERBOSE */
 
+static int
+sysctl_kern_threadpool_idle_ms(SYSCTLFN_ARGS)
+{
+       struct sysctlnode node;
+       int val, error;
+
+       node = *rnode;
+
+       val = threadpool_idle_time_ms;
+       node.sysctl_data = &val;
+       error = sysctl_lookup(SYSCTLFN_CALL(&node));
+       if (error == 0 && newp != NULL) {
+               /* Disallow negative values and 0 (forever). */
+               if (val < 1)
+                       error = EINVAL;
+               else
+                       threadpool_idle_time_ms = val;
+       }
+
+       return error;
+}
+
+SYSCTL_SETUP_PROTO(sysctl_threadpool_setup);
+
+SYSCTL_SETUP(sysctl_threadpool_setup,
+    "sysctl kern.threadpool subtree setup")
+{
+       const struct sysctlnode *rnode, *cnode;
+       int error __diagused;
+
+       error = sysctl_createv(clog, 0, NULL, &rnode,
+           CTLFLAG_PERMANENT,
+           CTLTYPE_NODE, "threadpool",
+           SYSCTL_DESCR("threadpool subsystem options"),
+           NULL, 0, NULL, 0,
+           CTL_KERN, CTL_CREATE, CTL_EOL);
+       KASSERT(error == 0);
+
+       error = sysctl_createv(clog, 0, &rnode, &cnode,
+           CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
+           CTLTYPE_INT, "idle_ms",
+           SYSCTL_DESCR("idle thread timeout in ms"),
+           sysctl_kern_threadpool_idle_ms, 0, NULL, 0,
+           CTL_CREATE, CTL_EOL);
+       KASSERT(error == 0);
+}
+
 void
 threadpools_init(void)
 {
@@ -980,7 +1028,7 @@
                                break;
                        }
                        if (cv_timedwait(&thread->tpt_cv, &pool->tp_lock,
-                               THREADPOOL_IDLE_TICKS))
+                               mstohz(threadpool_idle_time_ms)))
                                break;
                }
                if (__predict_false(thread->tpt_job == NULL)) {