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authorJosef Bacik <josef@redhat.com>2009-10-08 15:30:04 -0400
committerChris Mason <chris.mason@oracle.com>2009-10-08 15:30:04 -0400
commitff782e0a131c7f669445c07fe5c7ba91e043b7ed (patch)
treeff7773e6ce60bf977ed29897c13605f257647684
parente3ccfa989752c083ceb23c823a84f7ce3a081e61 (diff)
Btrfs: optimize fsync for the single writer case
This patch optimizes the tree logging stuff so it doesn't always wait 1 jiffie for new people to join the logging transaction if there is only ever 1 writer. This helps a little bit with latency where we have something like RPM where it will fdatasync every file it writes, and so waiting the 1 jiffie for every fdatasync really starts to add up. Signed-off-by: Josef Bacik <jbacik@redhat.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
-rw-r--r--fs/btrfs/ctree.h2
-rw-r--r--fs/btrfs/tree-log.c12
2 files changed, 13 insertions, 1 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a362dd617e97..16ddb19dda86 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1010,6 +1010,8 @@ struct btrfs_root {
1010 atomic_t log_commit[2]; 1010 atomic_t log_commit[2];
1011 unsigned long log_transid; 1011 unsigned long log_transid;
1012 unsigned long log_batch; 1012 unsigned long log_batch;
1013 pid_t log_start_pid;
1014 bool log_multiple_pids;
1013 1015
1014 u64 objectid; 1016 u64 objectid;
1015 u64 last_trans; 1017 u64 last_trans;
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 4d7d9abef42f..78f6254ac2d9 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -137,11 +137,20 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
137 137
138 mutex_lock(&root->log_mutex); 138 mutex_lock(&root->log_mutex);
139 if (root->log_root) { 139 if (root->log_root) {
140 if (!root->log_start_pid) {
141 root->log_start_pid = current->pid;
142 root->log_multiple_pids = false;
143 } else if (root->log_start_pid != current->pid) {
144 root->log_multiple_pids = true;
145 }
146
140 root->log_batch++; 147 root->log_batch++;
141 atomic_inc(&root->log_writers); 148 atomic_inc(&root->log_writers);
142 mutex_unlock(&root->log_mutex); 149 mutex_unlock(&root->log_mutex);
143 return 0; 150 return 0;
144 } 151 }
152 root->log_multiple_pids = false;
153 root->log_start_pid = current->pid;
145 mutex_lock(&root->fs_info->tree_log_mutex); 154 mutex_lock(&root->fs_info->tree_log_mutex);
146 if (!root->fs_info->log_root_tree) { 155 if (!root->fs_info->log_root_tree) {
147 ret = btrfs_init_log_root_tree(trans, root->fs_info); 156 ret = btrfs_init_log_root_tree(trans, root->fs_info);
@@ -1985,7 +1994,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
1985 if (atomic_read(&root->log_commit[(index1 + 1) % 2])) 1994 if (atomic_read(&root->log_commit[(index1 + 1) % 2]))
1986 wait_log_commit(trans, root, root->log_transid - 1); 1995 wait_log_commit(trans, root, root->log_transid - 1);
1987 1996
1988 while (1) { 1997 while (root->log_multiple_pids) {
1989 unsigned long batch = root->log_batch; 1998 unsigned long batch = root->log_batch;
1990 mutex_unlock(&root->log_mutex); 1999 mutex_unlock(&root->log_mutex);
1991 schedule_timeout_uninterruptible(1); 2000 schedule_timeout_uninterruptible(1);
@@ -2011,6 +2020,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
2011 root->log_batch = 0; 2020 root->log_batch = 0;
2012 root->log_transid++; 2021 root->log_transid++;
2013 log->log_transid = root->log_transid; 2022 log->log_transid = root->log_transid;
2023 root->log_start_pid = 0;
2014 smp_mb(); 2024 smp_mb();
2015 /* 2025 /*
2016 * log tree has been flushed to disk, new modifications of 2026 * log tree has been flushed to disk, new modifications of