mirror_zfs/include/sys/condvar.h
Brian Behlendorf 4d54fdee1d Reimplement mutexs for Linux lock profiling/analysis
For a generic explanation of why mutexs needed to be reimplemented
to work with the kernel lock profiling see commits:
  e811949a57 and
  d28db80fd0

The specific changes made to the mutex implemetation are as follows.
The Linux mutex structure is now directly embedded in the kmutex_t.
This allows a kmutex_t to be directly case to a mutex struct and
passed directly to the Linux primative.

Just like with the rwlocks it is critical that these functions be
implemented as '#defines to ensure the location information is
preserved.  The preprocessor can then do a direct replacement of
the Solaris primative with the linux primative.

Just as with the rwlocks we need to track the lock owner.  Here
things get a little more interesting because depending on your
kernel version, and how you've built your kernel Linux may already
do this for you.  If your running a 2.6.29 or newer kernel on a
SMP system the lock owner will be tracked.  This was added to Linux
to support adaptive mutexs, more on that shortly.  Alternately, your
kernel might track the lock owner if you've set CONFIG_DEBUG_MUTEXES
in the kernel build.  If neither of the above things is true for
your kernel the kmutex_t type will include and track the lock owner
to ensure correct behavior.  This is all handled by a new autoconf
check called SPL_AC_MUTEX_OWNER.

Concerning adaptive mutexs these are a very recent development and
they did not make it in to either the latest FC11 of SLES11 kernels.
Ideally, I'd love to see this kernel change appear in one of these
distros because it does help performance.  From Linux kernel commit:
  0d66bf6d3514b35eb6897629059443132992dbd7
  "Testing with Ingo's test-mutex application...
  gave a 345% boost for VFS scalability on my testbox"
However, if you don't want to backport this change yourself you
can still simply export the task_curr() symbol.  The kmutex_t
implementation will use this symbol when it's available to
provide it's own adaptive mutexs.

Finally, DEBUG_MUTEX support was removed including the proc handlers.
This was done because now that we are cleanly integrated with the
kernel profiling all this information and much much more is available
in debug kernel builds.  This code was now redundant.

Update mutexs validated on:
    - SLES10   (ppc64)
    - SLES11   (x86_64)
    - CHAOS4.2 (x86_64)
    - RHEL5.3  (x86_64)
    - RHEL6    (x86_64)
    - FC11     (x86_64)
2009-09-25 14:47:01 -07:00

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C

/*
* This file is part of the SPL: Solaris Porting Layer.
*
* Copyright (c) 2008 Lawrence Livermore National Security, LLC.
* Produced at Lawrence Livermore National Laboratory
* Written by:
* Brian Behlendorf <behlendorf1@llnl.gov>,
* Herb Wartens <wartens2@llnl.gov>,
* Jim Garlick <garlick@llnl.gov>
* UCRL-CODE-235197
*
* This 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.
*
* This 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 this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef _SPL_CONDVAR_H
#define _SPL_CONDVAR_H
#ifdef __cplusplus
extern "C" {
#endif
#include <linux/module.h>
#include <linux/wait.h>
#include <sys/kmem.h>
#include <sys/mutex.h>
/* The kcondvar_t struct is protected by mutex taken externally before
* calling any of the wait/signal funs, and passed into the wait funs.
*/
#define CV_MAGIC 0x346545f4
#define CV_POISON 0x95
typedef struct {
int cv_magic;
char *cv_name;
int cv_name_size;
wait_queue_head_t cv_event;
atomic_t cv_waiters;
kmutex_t *cv_mutex;
spinlock_t cv_lock;
} kcondvar_t;
typedef enum { CV_DEFAULT=0, CV_DRIVER } kcv_type_t;
extern void __cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg);
extern void __cv_destroy(kcondvar_t *cvp);
extern void __cv_wait(kcondvar_t *cvp, kmutex_t *mp);
extern clock_t __cv_timedwait(kcondvar_t *cvp, kmutex_t *mp,
clock_t expire_time);
extern void __cv_signal(kcondvar_t *cvp);
extern void __cv_broadcast(kcondvar_t *cvp);
#define cv_init(cvp, name, type, arg) \
({ \
if ((name) == NULL) \
__cv_init(cvp, #cvp, type, arg); \
else \
__cv_init(cvp, name, type, arg); \
})
#define cv_destroy(cvp) __cv_destroy(cvp)
#define cv_wait(cvp, mp) __cv_wait(cvp, mp)
#define cv_timedwait(cvp, mp, t) __cv_timedwait(cvp, mp, t)
#define cv_signal(cvp) __cv_signal(cvp)
#define cv_broadcast(cvp) __cv_broadcast(cvp)
#endif /* _SPL_CONDVAR_H */