Import adapted OpenSolaris' thread pool API implementation.

The thread pool is used by libzfs to implement parallel disk scanning.
Without this change our dummy wrapper made `zpool import ZZZ` command to
scan all disks sequentially from the single thread when searching for pools.
This change makes it use two threads per CPU, same as in OpenSolaris.

On system with 200 HDDs this change reduces ZFS pool import time from 35
to 22 seconds.

1 files changed, 99 insertions, 0 deletions

diff --git a/cddl/compat/opensolaris/misc/thread_pool_impl.h b/cddl/compat/opensolaris/misc/thread_pool_impl.h
new file mode 100644
index 000000000000..bc98ac8b1b37
--- /dev/null
+++ b/cddl/compat/opensolaris/misc/thread_pool_impl.h
@@ -0,0 +1,99 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+/*
+ * $FreeBSD$
+ */
+
+#ifndef _THREAD_POOL_IMPL_H
+#define	_THREAD_POOL_IMPL_H
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#include <thread_pool.h>
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+/*
+ * Thread pool implementation definitions.
+ * See <thread_pool.h> for interface declarations.
+ */
+
+/*
+ * FIFO queued job
+ */
+typedef struct tpool_job tpool_job_t;
+struct tpool_job {
+	tpool_job_t	*tpj_next;		/* list of jobs */
+	void		(*tpj_func)(void *);	/* function to call */
+	void		*tpj_arg;		/* its argument */
+};
+
+/*
+ * List of active threads, linked through their stacks.
+ */
+typedef struct tpool_active tpool_active_t;
+struct tpool_active {
+	tpool_active_t	*tpa_next;	/* list of active threads */
+	pthread_t	tpa_tid;	/* active thread id */
+};
+
+/*
+ * The thread pool.
+ */
+struct tpool {
+	tpool_t		*tp_forw;	/* circular list of all thread pools */
+	tpool_t		*tp_back;
+	mutex_t		tp_mutex;	/* protects the pool data */
+	cond_t		tp_busycv;	/* synchronization in tpool_dispatch */
+	cond_t		tp_workcv;	/* synchronization with workers */
+	cond_t		tp_waitcv;	/* synchronization in tpool_wait() */
+	tpool_active_t	*tp_active;	/* threads performing work */
+	tpool_job_t	*tp_head;	/* FIFO job queue */
+	tpool_job_t	*tp_tail;
+	pthread_attr_t	tp_attr;	/* attributes of the workers */
+	int		tp_flags;	/* see below */
+	uint_t		tp_linger;	/* seconds before idle workers exit */
+	int		tp_njobs;	/* number of jobs in job queue */
+	int		tp_minimum;	/* minimum number of worker threads */
+	int		tp_maximum;	/* maximum number of worker threads */
+	int		tp_current;	/* current number of worker threads */
+	int		tp_idle;	/* number of idle workers */
+};
+
+/* tp_flags */
+#define	TP_WAIT		0x01		/* waiting in tpool_wait() */
+#define	TP_SUSPEND	0x02		/* pool is being suspended */
+#define	TP_DESTROY	0x04		/* pool is being destroyed */
+#define	TP_ABANDON	0x08		/* pool is abandoned (auto-destroy) */
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif /* _THREAD_POOL_IMPL_H */