From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Thu, 9 Jul 2009 17:07:52 +0000 (-0700)
Subject: Add basic support for TASKQ_THREADS_CPU_PCT taskq flag which is
X-Git-Tag: zfs-0.8.0-rc1~152^2~687
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=915404bd509e5231c134042560d86e3ac86c1ab4;p=zfs

Add basic support for TASKQ_THREADS_CPU_PCT taskq flag which is
used to scale the number of threads based on the number of online
CPUs.  As CPUs are added/removed we should rescale the thread
count appropriately, but currently this is only done at create.
---

diff --git a/include/sys/taskq.h b/include/sys/taskq.h
index 0b8623103..603fde680 100644
--- a/include/sys/taskq.h
+++ b/include/sys/taskq.h
@@ -44,6 +44,7 @@ extern "C" {
 #define TASKQ_PREPOPULATE       0x00000001
 #define TASKQ_CPR_SAFE          0x00000002
 #define TASKQ_DYNAMIC           0x00000004
+#define TASKQ_THREADS_CPU_PCT   0x00000008
 
 typedef unsigned long taskqid_t;
 typedef void (task_func_t)(void *);
diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c
index 5960761f4..7575aa3b0 100644
--- a/module/spl/spl-taskq.c
+++ b/module/spl/spl-taskq.c
@@ -375,6 +375,15 @@ __taskq_create(const char *name, int nthreads, pri_t pri,
         ASSERT(maxalloc <= INT_MAX);
         ASSERT(!(flags & (TASKQ_CPR_SAFE | TASKQ_DYNAMIC))); /* Unsupported */
 
+	/* Scale the number of threads using nthreads as a percentage */
+	if (flags & TASKQ_THREADS_CPU_PCT) {
+		ASSERT(nthreads <= 100);
+		ASSERT(nthreads >= 0);
+		nthreads = MIN(nthreads, 100);
+		nthreads = MAX(nthreads, 0);
+		nthreads = MAX((num_online_cpus() * nthreads) / 100, 1);
+	}
+
         tq = kmem_alloc(sizeof(*tq), KM_SLEEP);
         if (tq == NULL)
                 RETURN(NULL);