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linux/fs/nilfs2/the_nilfs.h
Jiro SEKIBA 1cf58fa840 nilfs2: shorten freeze period due to GC in write operation v3 
This is a re-revised patch to shorten freeze period.
This version include a fix of the bug Konishi-san mentioned last time.

When GC is runnning, GC moves live block to difference segments.
Copying live blocks into memory is done in a transaction,
however it is not necessarily to be in the transaction.
This patch will get the nilfs_ioctl_move_blocks() out from
transaction lock and put it before the transaction.

I ran sysbench fileio test against nilfs partition.
I copied some DVD/CD images and created snapshot to create live blocks
before starting the benchmark.

Followings are summary of rc8 and rc8 w/ the patch of per-request
statistics, which is min/max and avg.  I ran each test three times and
bellow is average of those numers.

According to this benchmark result, average time is slightly degrated.
However, worstcase (max) result is significantly improved.
This can address a few seconds write freeze.

- random write per-request performance of rc8
 min   0.843ms
 max 680.406ms
 avg   3.050ms
- random write per-request performance of rc8 w/ this patch
 min   0.843ms -> 100.00%
 max 380.490ms ->  55.90%
 avg   3.233ms -> 106.00%

- sequential write per-request performance of rc8
 min   0.736ms
 max 774.343ms
 avg   2.883ms
- sequential write per-request performance of rc8 w/ this patch
 min   0.720ms ->  97.80%
 max  644.280ms->  83.20%
 avg   3.130ms -> 108.50%

-----8<-----8<-----nilfs_cleanerd.conf-----8<-----8<-----
protection_period       150
selection_policy        timestamp       # timestamp in ascend order
nsegments_per_clean     2
cleaning_interval       2
retry_interval          60
use_mmap
log_priority            info
-----8<-----8<-----nilfs_cleanerd.conf-----8<-----8<-----

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2009-09-14 18:27:15 +09:00

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/*
* the_nilfs.h - the_nilfs shared structure.
*
* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
*
* This program 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 program 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 St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Written by Ryusuke Konishi <ryusuke@osrg.net>
*
*/
#ifndef _THE_NILFS_H
#define _THE_NILFS_H
#include <linux/types.h>
#include <linux/buffer_head.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include "sb.h"
/* the_nilfs struct */
enum {
THE_NILFS_INIT = 0, /* Information from super_block is set */
THE_NILFS_LOADED, /* Roll-back/roll-forward has done and
the latest checkpoint was loaded */
THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
THE_NILFS_GC_RUNNING, /* gc process is running */
};
/**
* struct the_nilfs - struct to supervise multiple nilfs mount points
* @ns_flags: flags
* @ns_count: reference count
* @ns_list: list head for nilfs_list
* @ns_bdev: block device
* @ns_bdi: backing dev info
* @ns_writer: back pointer to writable nilfs_sb_info
* @ns_sem: semaphore for shared states
* @ns_super_sem: semaphore for global operations across super block instances
* @ns_mount_mutex: mutex protecting mount process of nilfs
* @ns_writer_sem: semaphore protecting ns_writer attach/detach
* @ns_current: back pointer to current mount
* @ns_sbh: buffer heads of on-disk super blocks
* @ns_sbp: pointers to super block data
* @ns_sbwtime: previous write time of super blocks
* @ns_sbsize: size of valid data in super block
* @ns_supers: list of nilfs super block structs
* @ns_seg_seq: segment sequence counter
* @ns_segnum: index number of the latest full segment.
* @ns_nextnum: index number of the full segment index to be used next
* @ns_pseg_offset: offset of next partial segment in the current full segment
* @ns_cno: next checkpoint number
* @ns_ctime: write time of the last segment
* @ns_nongc_ctime: write time of the last segment not for cleaner operation
* @ns_ndirtyblks: Number of dirty data blocks
* @ns_last_segment_lock: lock protecting fields for the latest segment
* @ns_last_pseg: start block number of the latest segment
* @ns_last_seq: sequence value of the latest segment
* @ns_last_cno: checkpoint number of the latest segment
* @ns_prot_seq: least sequence number of segments which must not be reclaimed
* @ns_free_segments_count: counter of free segments
* @ns_segctor_sem: segment constructor semaphore
* @ns_dat: DAT file inode
* @ns_cpfile: checkpoint file inode
* @ns_sufile: segusage file inode
* @ns_gc_dat: shadow inode of the DAT file inode for GC
* @ns_gc_inodes: dummy inodes to keep live blocks
* @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks
* @ns_blocksize_bits: bit length of block size
* @ns_nsegments: number of segments in filesystem
* @ns_blocks_per_segment: number of blocks per segment
* @ns_r_segments_percentage: reserved segments percentage
* @ns_nrsvsegs: number of reserved segments
* @ns_first_data_block: block number of first data block
* @ns_inode_size: size of on-disk inode
* @ns_first_ino: first not-special inode number
* @ns_crc_seed: seed value of CRC32 calculation
*/
struct the_nilfs {
unsigned long ns_flags;
atomic_t ns_count;
struct list_head ns_list;
struct block_device *ns_bdev;
struct backing_dev_info *ns_bdi;
struct nilfs_sb_info *ns_writer;
struct rw_semaphore ns_sem;
struct rw_semaphore ns_super_sem;
struct mutex ns_mount_mutex;
struct rw_semaphore ns_writer_sem;
/*
* components protected by ns_super_sem
*/
struct nilfs_sb_info *ns_current;
struct list_head ns_supers;
/*
* used for
* - loading the latest checkpoint exclusively.
* - allocating a new full segment.
* - protecting s_dirt in the super_block struct
* (see nilfs_write_super) and the following fields.
*/
struct buffer_head *ns_sbh[2];
struct nilfs_super_block *ns_sbp[2];
time_t ns_sbwtime[2];
unsigned ns_sbsize;
unsigned ns_mount_state;
/*
* Following fields are dedicated to a writable FS-instance.
* Except for the period seeking checkpoint, code outside the segment
* constructor must lock a segment semaphore while accessing these
* fields.
* The writable FS-instance is sole during a lifetime of the_nilfs.
*/
u64 ns_seg_seq;
__u64 ns_segnum;
__u64 ns_nextnum;
unsigned long ns_pseg_offset;
__u64 ns_cno;
time_t ns_ctime;
time_t ns_nongc_ctime;
atomic_t ns_ndirtyblks;
/*
* The following fields hold information on the latest partial segment
* written to disk with a super root. These fields are protected by
* ns_last_segment_lock.
*/
spinlock_t ns_last_segment_lock;
sector_t ns_last_pseg;
u64 ns_last_seq;
__u64 ns_last_cno;
u64 ns_prot_seq;
unsigned long ns_free_segments_count;
struct rw_semaphore ns_segctor_sem;
/*
* Following fields are lock free except for the period before
* the_nilfs is initialized.
*/
struct inode *ns_dat;
struct inode *ns_cpfile;
struct inode *ns_sufile;
struct inode *ns_gc_dat;
/* GC inode list and hash table head */
struct list_head ns_gc_inodes;
struct hlist_head *ns_gc_inodes_h;
/* Disk layout information (static) */
unsigned int ns_blocksize_bits;
unsigned long ns_nsegments;
unsigned long ns_blocks_per_segment;
unsigned long ns_r_segments_percentage;
unsigned long ns_nrsvsegs;
unsigned long ns_first_data_block;
int ns_inode_size;
int ns_first_ino;
u32 ns_crc_seed;
};
#define NILFS_GCINODE_HASH_BITS 8
#define NILFS_GCINODE_HASH_SIZE (1<<NILFS_GCINODE_HASH_BITS)
#define THE_NILFS_FNS(bit, name) \
static inline void set_nilfs_##name(struct the_nilfs *nilfs) \
{ \
set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
} \
static inline void clear_nilfs_##name(struct the_nilfs *nilfs) \
{ \
clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
} \
static inline int nilfs_##name(struct the_nilfs *nilfs) \
{ \
return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
}
THE_NILFS_FNS(INIT, init)
THE_NILFS_FNS(LOADED, loaded)
THE_NILFS_FNS(DISCONTINUED, discontinued)
THE_NILFS_FNS(GC_RUNNING, gc_running)
/* Minimum interval of periodical update of superblocks (in seconds) */
#define NILFS_SB_FREQ 10
#define NILFS_ALTSB_FREQ 60 /* spare superblock */
static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
{
u64 t = get_seconds();
return t < nilfs->ns_sbwtime[0] ||
t > nilfs->ns_sbwtime[0] + NILFS_SB_FREQ;
}
static inline int nilfs_altsb_need_update(struct the_nilfs *nilfs)
{
u64 t = get_seconds();
struct nilfs_super_block **sbp = nilfs->ns_sbp;
return sbp[1] && t > nilfs->ns_sbwtime[1] + NILFS_ALTSB_FREQ;
}
void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
struct the_nilfs *find_or_create_nilfs(struct block_device *);
void put_nilfs(struct the_nilfs *);
int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
int nilfs_near_disk_full(struct the_nilfs *);
void nilfs_fall_back_super_block(struct the_nilfs *);
void nilfs_swap_super_block(struct the_nilfs *);
static inline void get_nilfs(struct the_nilfs *nilfs)
{
/* Caller must have at least one reference of the_nilfs. */
atomic_inc(&nilfs->ns_count);
}
static inline void
nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
{
down_write(&nilfs->ns_writer_sem);
nilfs->ns_writer = sbi;
up_write(&nilfs->ns_writer_sem);
}
static inline void
nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
{
down_write(&nilfs->ns_writer_sem);
if (sbi == nilfs->ns_writer)
nilfs->ns_writer = NULL;
up_write(&nilfs->ns_writer_sem);
}
static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)
{
if (atomic_dec_and_test(&sbi->s_count))
kfree(sbi);
}
static inline void
nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
sector_t *seg_start, sector_t *seg_end)
{
*seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
*seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
if (segnum == 0)
*seg_start = nilfs->ns_first_data_block;
}
static inline sector_t
nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
{
return (segnum == 0) ? nilfs->ns_first_data_block :
(sector_t)nilfs->ns_blocks_per_segment * segnum;
}
static inline __u64
nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
{
sector_t segnum = blocknr;
sector_div(segnum, nilfs->ns_blocks_per_segment);
return segnum;
}
static inline void
nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
sector_t seg_end)
{
/* terminate the current full segment (used in case of I/O-error) */
nilfs->ns_pseg_offset = seg_end - seg_start + 1;
}
static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
{
/* move forward with a full segment */
nilfs->ns_segnum = nilfs->ns_nextnum;
nilfs->ns_pseg_offset = 0;
nilfs->ns_seg_seq++;
}
static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
{
__u64 cno;
spin_lock(&nilfs->ns_last_segment_lock);
cno = nilfs->ns_last_cno;
spin_unlock(&nilfs->ns_last_segment_lock);
return cno;
}
static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
{
return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
}
#endif /* _THE_NILFS_H */
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