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Emulate illumos interface cv_timedwait_hires()

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Needed for Illumos #3582. This interface is supposed to support
a variable-resolution timeout with nanosecond granularity.  This
implementation rounds up to microsecond resolution, as nanosecond-
precision timing is rarely needed for real-world performance
tuning and may incur unnecessary busy-waiting.  usleep_range() is
used if available, otherwise udelay() or msleep() are used
depending on the length of the delay interval.

Add flags from sys/callo.h as these are used to control the behavior of
cv_timedwait_hires().  Specifically,

CALLOUT_FLAG_ABSOLUTE
    Normally, the expiration passed to the timeout API functions is
    an expiration interval. If this flag is specified, then it is
    interpreted as the expiration time itself.

CALLOUT_FLAG_ROUNDUP
    Roundup the expiration time to the next resolution boundary. If this
    flag is not specified, the expiration time is rounded down.

References:
    https://www.illumos.org/issues/3582
    illumos/illumos-gate@0689f76

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #304
This commit is contained in:
Ned Bass
2013-11-01 13:37:58 -07:00
committed by Brian Behlendorf
parent 0f4b9a5806
commit 184c687387
8 changed files with 212 additions and 0 deletions
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include/linux/Makefile.am
+1
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@@ -3,6 +3,7 @@ COMMON_H =
KERNEL_H = \
$(top_srcdir)/include/linux/bitops_compat.h \
$(top_srcdir)/include/linux/compiler_compat.h \
$(top_srcdir)/include/linux/delay_compat.h \
$(top_srcdir)/include/linux/file_compat.h \
$(top_srcdir)/include/linux/kallsyms_compat.h \
$(top_srcdir)/include/linux/list_compat.h \
include/linux/delay_compat.h
+47
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@@ -0,0 +1,47 @@
/*****************************************************************************\
* Copyright (C) 2007-2013 Lawrence Livermore National Security, LLC.
* Copyright (C) 2007 The Regents of the University of California.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
* UCRL-CODE-235197
*
* This file is part of the SPL, Solaris Porting Layer.
* For details, see <http://zfsonlinux.org/>.
*
* The SPL is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* The SPL is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with the SPL. If not, see <http://www.gnu.org/licenses/>.
\*****************************************************************************/
#ifndef _SPL_DELAY_COMPAT_H
#define _SPL_DELAY_COMPAT_H
#include <linux/delay.h>
#include <linux/time.h>
/* usleep_range() introduced in 2.6.36 */
#ifndef HAVE_USLEEP_RANGE
static inline void
usleep_range(unsigned long min, unsigned long max)
{
unsigned int min_ms = min / USEC_PER_MSEC;
if (min >= MAX_UDELAY_MS)
msleep(min_ms);
else
udelay(min);
}
#endif /* HAVE_USLEEP_RANGE */
#endif /* _SPL_DELAY_COMPAT_H */