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freebsd-nq/zfs_config.h.in
Brian Behlendorf ab26409db7 Linux 3.1 compat, super_block->s_shrink 
The Linux 3.1 kernel has introduced the concept of per-filesystem
shrinkers which are directly assoicated with a super block.  Prior
to this change there was one shared global shrinker.

The zfs code relied on being able to call the global shrinker when
the arc_meta_limit was exceeded.  This would cause the VFS to drop
references on a fraction of the dentries in the dcache.  The ARC
could then safely reclaim the memory used by these entries and
honor the arc_meta_limit.  Unfortunately, when per-filesystem
shrinkers were added the old interfaces were made unavailable.

This change adds support to use the new per-filesystem shrinker
interface so we can continue to honor the arc_meta_limit.  The
major benefit of the new interface is that we can now target
only the zfs filesystem for dentry and inode pruning.  Thus we
can minimize any impact on the caching of other filesystems.

In the context of making this change several other important
issues related to managing the ARC were addressed, they include:

* The dnlc_reduce_cache() function which was called by the ARC
to drop dentries for the Posix layer was replaced with a generic
zfs_prune_t callback.  The ZPL layer now registers a callback to
drop these dentries removing a layering violation which dates
back to the Solaris code.  This callback can also be used by
other ARC consumers such as Lustre.

  arc_add_prune_callback()
  arc_remove_prune_callback()

* The arc_reduce_dnlc_percent module option has been changed to
arc_meta_prune for clarity.  The dnlc functions are specific to
Solaris's VFS and have already been largely eliminated already.
The replacement tunable now represents the number of bytes the
prune callback will request when invoked.

* Less aggressively invoke the prune callback.  We used to call
this whenever we exceeded the arc_meta_limit however that's not
strictly correct since it results in over zeleous reclaim of
dentries and inodes.  It is now only called once the arc_meta_limit
is exceeded and every effort has been made to evict other data from
the ARC cache.

* More promptly manage exceeding the arc_meta_limit.  When reading
meta data in to the cache if a buffer was unable to be recycled
notify the arc_reclaim thread to invoke the required prune.

* Added arcstat_prune kstat which is incremented when the ARC
is forced to request that a consumer prune its cache.  Remember
this will only occur when the ARC has no other choice.  If it
can evict buffers safely without invoking the prune callback
it will.

* This change is also expected to resolve the unexpect collapses
of the ARC cache.  This would occur because when exceeded just the
arc_meta_limit reclaim presure would be excerted on the arc_c
value via arc_shrink().  This effectively shrunk the entire cache
when really we just needed to reclaim meta data.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #466
Closes #292
2012-01-11 11:46:02 -08:00

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/* zfs_config.h.in. Generated from configure.ac by autoheader. */
/* invalidate_bdev() wants 1 arg */
#undef HAVE_1ARG_INVALIDATE_BDEV
/* bio_end_io_t wants 2 args */
#undef HAVE_2ARGS_BIO_END_IO_T
/* security_inode_init_security wants 6 args */
#undef HAVE_6ARGS_SECURITY_INODE_INIT_SECURITY
/* struct block_device_operations use bdevs */
#undef HAVE_BDEV_BLOCK_DEVICE_OPERATIONS
/* bdev_logical_block_size() is available */
#undef HAVE_BDEV_LOGICAL_BLOCK_SIZE
/* struct super_block has s_bdi */
#undef HAVE_BDI
/* bdi_setup_and_register() is available */
#undef HAVE_BDI_SETUP_AND_REGISTER
/* bio_empy_barrier() is defined */
#undef HAVE_BIO_EMPTY_BARRIER
/* REQ_FAILFAST_MASK is defined */
#undef HAVE_BIO_REQ_FAILFAST_MASK
/* BIO_RW_FAILFAST is defined */
#undef HAVE_BIO_RW_FAILFAST
/* BIO_RW_FAILFAST_* are defined */
#undef HAVE_BIO_RW_FAILFAST_DTD
/* BIO_RW_SYNC is defined */
#undef HAVE_BIO_RW_SYNC
/* BIO_RW_SYNCIO is defined */
#undef HAVE_BIO_RW_SYNCIO
/* blkdev_get_by_path() is available */
#undef HAVE_BLKDEV_GET_BY_PATH
/* blk_end_request() is available */
#undef HAVE_BLK_END_REQUEST
/* blk_end_request() is GPL-only */
#undef HAVE_BLK_END_REQUEST_GPL_ONLY
/* blk_fetch_request() is available */
#undef HAVE_BLK_FETCH_REQUEST
/* blk_requeue_request() is available */
#undef HAVE_BLK_REQUEUE_REQUEST
/* blk_rq_bytes() is available */
#undef HAVE_BLK_RQ_BYTES
/* blk_rq_bytes() is GPL-only */
#undef HAVE_BLK_RQ_BYTES_GPL_ONLY
/* blk_rq_pos() is available */
#undef HAVE_BLK_RQ_POS
/* blk_rq_sectors() is available */
#undef HAVE_BLK_RQ_SECTORS
/* check_disk_size_change() is available */
#undef HAVE_CHECK_DISK_SIZE_CHANGE
/* super_block uses const struct xattr_hander */
#undef HAVE_CONST_XATTR_HANDLER
/* xattr_handler->get() wants dentry */
#undef HAVE_DENTRY_XATTR_GET
/* xattr_handler->set() wants dentry */
#undef HAVE_DENTRY_XATTR_SET
/* Define to 1 if you have the <dlfcn.h> header file. */
#undef HAVE_DLFCN_H
/* d_obtain_alias() is available */
#undef HAVE_D_OBTAIN_ALIAS
/* sops->evict_inode() exists */
#undef HAVE_EVICT_INODE
/* kernel defines fmode_t */
#undef HAVE_FMODE_T
/* sops->free_cached_objects() exists */
#undef HAVE_FREE_CACHED_OBJECTS
/* fops->fsync() with range */
#undef HAVE_FSYNC_RANGE
/* fops->fsync() without dentry */
#undef HAVE_FSYNC_WITHOUT_DENTRY
/* fops->fsync() with dentry */
#undef HAVE_FSYNC_WITH_DENTRY
/* blk_disk_ro() is available */
#undef HAVE_GET_DISK_RO
/* Define to 1 if licensed under the GPL */
#undef HAVE_GPL_ONLY_SYMBOLS
/* insert_inode_locked() is available */
#undef HAVE_INSERT_INODE_LOCKED
/* Define to 1 if you have the <inttypes.h> header file. */
#undef HAVE_INTTYPES_H
/* result=stropts.h Define to 1 if ioctl() defined in <stropts.h> */
#undef HAVE_IOCTL_IN_STROPTS_H
/* Define to 1 if ioctl() defined in <sys/ioctl.h> */
#undef HAVE_IOCTL_IN_SYS_IOCTL_H
/* Define to 1 if ioctl() defined in <unistd.h> */
#undef HAVE_IOCTL_IN_UNISTD_H
/* kernel defines KOBJ_NAME_LEN */
#undef HAVE_KOBJ_NAME_LEN
/* Define if you have libblkid */
#undef HAVE_LIBBLKID
/* Define if you have selinux */
#undef HAVE_LIBSELINUX
/* Define if you have libuuid */
#undef HAVE_LIBUUID
/* Define to 1 if you have the `z' library (-lz). */
#undef HAVE_LIBZ
/* Define to 1 if you have the <memory.h> header file. */
#undef HAVE_MEMORY_H
/* mount_nodev() is available */
#undef HAVE_MOUNT_NODEV
/* sops->nr_cached_objects() exists */
#undef HAVE_NR_CACHED_OBJECTS
/* open_bdev_exclusive() is available */
#undef HAVE_OPEN_BDEV_EXCLUSIVE
/* REQ_SYNC is defined */
#undef HAVE_REQ_SYNC
/* rq_for_each_segment() is available */
#undef HAVE_RQ_FOR_EACH_SEGMENT
/* rq_is_sync() is available */
#undef HAVE_RQ_IS_SYNC
/* set_nlink() is available */
#undef HAVE_SET_NLINK
/* struct super_block has s_shrink */
#undef HAVE_SHRINK
/* Define to 1 if you have the <stdint.h> header file. */
#undef HAVE_STDINT_H
/* Define to 1 if you have the <stdlib.h> header file. */
#undef HAVE_STDLIB_H
/* Define to 1 if you have the <strings.h> header file. */
#undef HAVE_STRINGS_H
/* Define to 1 if you have the <string.h> header file. */
#undef HAVE_STRING_H
/* Define to 1 if you have the <sys/stat.h> header file. */
#undef HAVE_SYS_STAT_H
/* Define to 1 if you have the <sys/types.h> header file. */
#undef HAVE_SYS_TYPES_H
/* truncate_setsize() is available */
#undef HAVE_TRUNCATE_SETSIZE
/* Define to 1 if you have the <unistd.h> header file. */
#undef HAVE_UNISTD_H
/* Define if you have zlib */
#undef HAVE_ZLIB
/* Define to the sub-directory in which libtool stores uninstalled libraries.
*/
#undef LT_OBJDIR
/* Define to 1 if NPTL threading implementation includes guard area in stack
allocation */
#undef NPTL_GUARD_WITHIN_STACK
/* Name of package */
#undef PACKAGE
/* Define to the address where bug reports for this package should be sent. */
#undef PACKAGE_BUGREPORT
/* Define to the full name of this package. */
#undef PACKAGE_NAME
/* Define to the full name and version of this package. */
#undef PACKAGE_STRING
/* Define to the one symbol short name of this package. */
#undef PACKAGE_TARNAME
/* Define to the version of this package. */
#undef PACKAGE_VERSION
/* Define to 1 if you have the ANSI C header files. */
#undef STDC_HEADERS
/* Version number of package */
#undef VERSION
/* Define the project alias string. */
#undef ZFS_META_ALIAS
/* Define the project author. */
#undef ZFS_META_AUTHOR
/* Define the project release date. */
#undef ZFS_META_DATA
/* Define the project license. */
#undef ZFS_META_LICENSE
/* Define the libtool library 'age' version information. */
#undef ZFS_META_LT_AGE
/* Define the libtool library 'current' version information. */
#undef ZFS_META_LT_CURRENT
/* Define the libtool library 'revision' version information. */
#undef ZFS_META_LT_REVISION
/* Define the project name. */
#undef ZFS_META_NAME
/* Define the project release. */
#undef ZFS_META_RELEASE
/* Define the project version. */
#undef ZFS_META_VERSION
#undef PACKAGE
#undef PACKAGE_BUGREPORT
#undef PACKAGE_NAME
#undef PACKAGE_STRING
#undef PACKAGE_TARNAME
#undef PACKAGE_VERSION
#undef STDC_HEADERS
#undef VERSION
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