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Date: Mon, 9 May 2011 19:41:41 +0300
From: amir73il@...rs.sourceforge.net
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, Amir Goldstein <amir73il@...rs.sf.net>,
Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: [PATCH RFC 23/30] ext4: snapshot journaled - trace COW/buffer credits
From: Amir Goldstein <amir73il@...rs.sf.net>
Extra debug prints to trace snapshot usage of buffer credits.
Signed-off-by: Amir Goldstein <amir73il@...rs.sf.net>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
---
fs/ext4/ext4_jbd2.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++
fs/ext4/ext4_jbd2.h | 26 ++++++++++++++++
fs/ext4/super.c | 2 +
3 files changed, 108 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index e8287f4..eb88564 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -23,6 +23,7 @@ int __ext4_handle_get_bitmap_access(const char *where, unsigned int line,
if (err)
ext4_journal_abort_handle(where, line, __func__, bh,
handle, err);
+ ext4_journal_trace(SNAP_DEBUG, where, handle, 1);
}
return err;
}
@@ -40,6 +41,7 @@ int __ext4_journal_get_write_access_inode(const char *where, unsigned int line,
if (err)
ext4_journal_abort_handle(where, line, __func__, bh,
handle, err);
+ ext4_journal_trace(SNAP_DEBUG, where, handle, 1);
}
return err;
}
@@ -91,6 +93,7 @@ int __ext4_forget(const char *where, unsigned int line, handle_t *handle,
if (err)
ext4_journal_abort_handle(where, line, __func__,
bh, handle, err);
+ ext4_journal_trace(SNAP_DEBUG, where, handle, 1);
return err;
}
return 0;
@@ -108,6 +111,7 @@ int __ext4_forget(const char *where, unsigned int line, handle_t *handle,
"error %d when attempting revoke", err);
}
BUFFER_TRACE(bh, "exit");
+ ext4_journal_trace(SNAP_DEBUG, where, handle, 1);
return err;
}
@@ -123,6 +127,7 @@ int __ext4_journal_get_create_access(const char *where, unsigned int line,
if (err)
ext4_journal_abort_handle(where, line, __func__,
bh, handle, err);
+ ext4_journal_trace(SNAP_DEBUG, where, handle, -1);
}
return err;
}
@@ -198,6 +203,7 @@ int __ext4_handle_dirty_metadata(const char *where, unsigned int line,
}
jbd_unlock_bh_state(bh);
}
+ ext4_journal_trace(SNAP_DEBUG, where, handle, -1);
} else {
if (inode)
mark_buffer_dirty_inode(bh, inode);
@@ -236,3 +242,77 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
sb->s_dirt = 1;
return err;
}
+
+#ifdef CONFIG_JBD2_DEBUG
+static void ext4_journal_cow_stats(int n, handle_t *handle)
+{
+ snapshot_debug(n, "COW stats: moved/copied=%d/%d, "
+ "mapped/bitmap/cached=%d/%d/%d, "
+ "bitmaps/cleared=%d/%d\n", handle->h_cow_moved,
+ handle->h_cow_copied, handle->h_cow_ok_mapped,
+ handle->h_cow_ok_bitmap, handle->h_cow_ok_jh,
+ handle->h_cow_bitmaps, handle->h_cow_excluded);
+}
+#else
+#define ext4_journal_cow_stats(n, handle)
+#endif
+
+#ifdef CONFIG_EXT4_DEBUG
+void __ext4_journal_trace(int n, const char *fn, const char *caller,
+ handle_t *handle, int nblocks)
+{
+ int active_snapshot;
+ int upper;
+ int lower;
+ int final;
+ struct super_block *sb;
+
+ sb = handle->h_transaction->t_journal->j_private;
+ if (!EXT4_SNAPSHOTS(sb))
+ return;
+
+ active_snapshot = ext4_snapshot_active(EXT4_SB(sb));
+ upper = EXT4_SNAPSHOT_START_TRANS_BLOCKS(handle->h_base_credits);
+ lower = EXT4_SNAPSHOT_TRANS_BLOCKS(handle->h_user_credits);
+ final = (nblocks == 0 && handle->h_ref == 1 &&
+ !IS_COWING(handle));
+
+ switch (snapshot_enable_debug) {
+ case SNAP_INFO:
+ /* trace final journal_stop if any credits have been used */
+ if (final && (handle->h_buffer_credits < upper ||
+ handle->h_user_credits < handle->h_base_credits))
+ break;
+ case SNAP_WARN:
+ /*
+ * trace if buffer credits are too low - lower limit is only
+ * valid if there is an active snapshot and not during COW
+ */
+ if (handle->h_buffer_credits < lower &&
+ active_snapshot && !IS_COWING(handle))
+ break;
+ case SNAP_ERR:
+ /* trace if user credits are too low */
+ if (handle->h_user_credits < 0)
+ break;
+ case 0:
+ /* no trace */
+ return;
+
+ case SNAP_DEBUG:
+ default:
+ /* trace all calls */
+ break;
+ }
+
+ snapshot_debug_l(n, IS_COWING(handle), "%s(%d): credits=%d,"
+ " limit=%d/%d, user=%d/%d, ref=%d, caller=%s\n",
+ fn, nblocks, handle->h_buffer_credits, lower, upper,
+ handle->h_user_credits, handle->h_base_credits,
+ handle->h_ref, caller);
+ if (!final)
+ return;
+
+ ext4_journal_cow_stats(n, handle);
+}
+#endif
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 1e05e2c..ff8dcd8 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -229,10 +229,36 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
#define ext4_handle_dirty_super(handle, sb) \
__ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb))
+/*
+ * macros for ext4 to update transaction COW statistics.
+ * if the kernel was compiled without CONFIG_JBD2_DEBUG
+ * then the h_cow_* fields are not allocated in handle objects.
+ */
+#ifdef CONFIG_JBD2_DEBUG
+#define trace_cow_add(handle, name, num) \
+ (handle)->h_cow_##name += (num)
+#define trace_cow_inc(handle, name) \
+ (handle)->h_cow_##name++;
+
+#else
#define trace_cow_add(handle, name, num)
#define trace_cow_inc(handle, name)
+#endif
+#ifdef CONFIG_EXT4_DEBUG
+void __ext4_journal_trace(int debug, const char *fn, const char *caller,
+ handle_t *handle, int nblocks);
+
+#define ext4_journal_trace(n, caller, handle, nblocks) \
+ do { \
+ if ((n) <= snapshot_enable_debug) \
+ __ext4_journal_trace((n), __func__, (caller), \
+ (handle), (nblocks)); \
+ } while (0)
+
+#else
#define ext4_journal_trace(n, caller, handle, nblocks)
+#endif
handle_t *__ext4_journal_start(const char *where,
struct super_block *sb, int nblocks);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 0bde939..9f68ed1 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -308,6 +308,8 @@ int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle)
int err;
int rc;
+ ext4_journal_trace(SNAP_WARN, where, handle, 0);
+
if (!ext4_handle_valid(handle)) {
ext4_put_nojournal(handle);
return 0;
--
1.7.0.4
--
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