[lustre-devel] [PATCH 03/22] ext4: prealloc table optimization

[James Simmons <jsimmons@infradead.org>]

Optimize prealloc table

Signed-off-by: James Simmons <jsimmons@infradead.org>
---
 fs/ext4/ext4.h    |   7 +-
 fs/ext4/inode.c   |   3 +
 fs/ext4/mballoc.c | 221 +++++++++++++++++++++++++++++++++++++++++-------------
 fs/ext4/namei.c   |   4 +-
 fs/ext4/sysfs.c   |   8 +-
 5 files changed, 186 insertions(+), 57 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 8abbcab..423ab4d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1190,6 +1190,8 @@ struct ext4_inode_info {
 /* Metadata checksum algorithm codes */
 #define EXT4_CRC32C_CHKSUM		1
 
+#define EXT4_MAX_PREALLOC_TABLE		64
+
 /*
  * Structure of the super block
  */
@@ -1447,12 +1449,14 @@ struct ext4_sb_info {
 
 	/* tunables */
 	unsigned long s_stripe;
-	unsigned int s_mb_stream_request;
+	unsigned long s_mb_small_req;
+	unsigned long s_mb_large_req;
 	unsigned int s_mb_max_to_scan;
 	unsigned int s_mb_min_to_scan;
 	unsigned int s_mb_stats;
 	unsigned int s_mb_order2_reqs;
 	unsigned int s_mb_group_prealloc;
+	unsigned long *s_mb_prealloc_table;
 	unsigned int s_max_dir_size_kb;
 	/* where last allocation was done - for stream allocation */
 	unsigned long s_mb_last_group;
@@ -2457,6 +2461,7 @@ extern int ext4_init_inode_table(struct super_block *sb,
 extern void ext4_end_bitmap_read(struct buffer_head *bh, int uptodate);
 
 /* mballoc.c */
+extern const struct file_operations ext4_seq_prealloc_table_fops;
 extern const struct seq_operations ext4_mb_seq_groups_ops;
 extern long ext4_mb_stats;
 extern long ext4_mb_max_to_scan;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 6e66175..c37418a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2796,6 +2796,9 @@ static int ext4_writepages(struct address_space *mapping,
 		ext4_journal_stop(handle);
 	}
 
+	if (wbc->nr_to_write < sbi->s_mb_small_req)
+		wbc->nr_to_write = sbi->s_mb_small_req;
+
 	if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 		range_whole = 1;
 
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 99ba720..3be3bef 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2339,6 +2339,101 @@ static void ext4_mb_seq_groups_stop(struct seq_file *seq, void *v)
 	.show   = ext4_mb_seq_groups_show,
 };
 
+static int ext4_mb_check_and_update_prealloc(struct ext4_sb_info *sbi,
+					     char *str, size_t cnt,
+					     int update)
+{
+	unsigned long value;
+	unsigned long prev = 0;
+	char *cur;
+	char *next;
+	char *end;
+	int num = 0;
+
+	cur = str;
+	end = str + cnt;
+	while (cur < end) {
+		while ((cur < end) && (*cur == ' ')) cur++;
+		/* Yuck - simple_strtol */
+		value = simple_strtol(cur, &next, 0);
+		if (value == 0)
+			break;
+		if (cur == next)
+			return -EINVAL;
+
+		cur = next;
+
+		if (value > (sbi->s_blocks_per_group - 1 - 1 - sbi->s_itb_per_group))
+			return -EINVAL;
+
+		/* they should add values in order */
+		if (value <= prev)
+			return -EINVAL;
+
+		if (update)
+			sbi->s_mb_prealloc_table[num] = value;
+
+		prev = value;
+		num++;
+	}
+
+	if (num > EXT4_MAX_PREALLOC_TABLE - 1)
+		return -EOVERFLOW;
+
+	if (update)
+		sbi->s_mb_prealloc_table[num] = 0;
+
+	return 0;
+}
+
+static ssize_t ext4_mb_prealloc_table_proc_write(struct file *file,
+						 const char __user *buf,
+						 size_t cnt, loff_t *pos)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(PDE_DATA(file_inode(file)));
+	char str[128];
+	int rc;
+
+	if (cnt >= sizeof(str))
+		return -EINVAL;
+	if (copy_from_user(str, buf, cnt))
+		return -EFAULT;
+
+	rc = ext4_mb_check_and_update_prealloc(sbi, str, cnt, 0);
+	if (rc)
+		return rc;
+
+	rc = ext4_mb_check_and_update_prealloc(sbi, str, cnt, 1);
+	return rc ? rc : cnt;
+}
+
+static int mb_prealloc_table_seq_show(struct seq_file *m, void *v)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(m->private);
+	int i;
+
+	for (i = 0; i < EXT4_MAX_PREALLOC_TABLE &&
+			sbi->s_mb_prealloc_table[i] != 0; i++)
+		seq_printf(m, "%ld ", sbi->s_mb_prealloc_table[i]);
+	seq_printf(m, "\n");
+
+	return 0;
+}
+
+static int mb_prealloc_table_seq_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, mb_prealloc_table_seq_show, PDE_DATA(inode));
+}
+
+const struct file_operations ext4_seq_prealloc_table_fops = {
+	.owner	 = THIS_MODULE,
+	.open	 = mb_prealloc_table_seq_open,
+	.read	 = seq_read,
+	.llseek	 = seq_lseek,
+	.release = single_release,
+	.write	 = ext4_mb_prealloc_table_proc_write,
+};
+
 static struct kmem_cache *get_groupinfo_cache(int blocksize_bits)
 {
 	int cache_index = blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
@@ -2567,7 +2662,7 @@ static int ext4_groupinfo_create_slab(size_t size)
 int ext4_mb_init(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	unsigned i, j;
+	unsigned i, j, k, l;
 	unsigned offset, offset_incr;
 	unsigned max;
 	int ret;
@@ -2616,7 +2711,6 @@ int ext4_mb_init(struct super_block *sb)
 	sbi->s_mb_max_to_scan = MB_DEFAULT_MAX_TO_SCAN;
 	sbi->s_mb_min_to_scan = MB_DEFAULT_MIN_TO_SCAN;
 	sbi->s_mb_stats = MB_DEFAULT_STATS;
-	sbi->s_mb_stream_request = MB_DEFAULT_STREAM_THRESHOLD;
 	sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS;
 	/*
 	 * The default group preallocation is 512, which for 4k block
@@ -2640,9 +2734,28 @@ int ext4_mb_init(struct super_block *sb)
 	 * RAID stripe size so that preallocations don't fragment
 	 * the stripes.
 	 */
-	if (sbi->s_stripe > 1) {
-		sbi->s_mb_group_prealloc = roundup(
-			sbi->s_mb_group_prealloc, sbi->s_stripe);
+	/* Allocate table once */
+	sbi->s_mb_prealloc_table = kzalloc(
+		EXT4_MAX_PREALLOC_TABLE * sizeof(unsigned long), GFP_NOFS);
+	if (!sbi->s_mb_prealloc_table) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (sbi->s_stripe == 0) {
+		for (k = 0, l = 4; k <= 9; ++k, l *= 2)
+			sbi->s_mb_prealloc_table[k] = l;
+
+		sbi->s_mb_small_req = 256;
+		sbi->s_mb_large_req = 1024;
+		sbi->s_mb_group_prealloc = 512;
+	} else {
+		for (k = 0, l = sbi->s_stripe; k <= 2; ++k, l *= 2)
+			sbi->s_mb_prealloc_table[k] = l;
+
+		sbi->s_mb_small_req = sbi->s_stripe;
+		sbi->s_mb_large_req = sbi->s_stripe * 8;
+		sbi->s_mb_group_prealloc = sbi->s_stripe * 4;
 	}
 
 	sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
@@ -2670,6 +2783,7 @@ int ext4_mb_init(struct super_block *sb)
 	free_percpu(sbi->s_locality_groups);
 	sbi->s_locality_groups = NULL;
 out:
+	kfree(sbi->s_mb_prealloc_table);
 	kfree(sbi->s_mb_offsets);
 	sbi->s_mb_offsets = NULL;
 	kfree(sbi->s_mb_maxs);
@@ -2932,7 +3046,6 @@ void ext4_exit_mballoc(void)
 	int err, len;
 
 	BUG_ON(ac->ac_status != AC_STATUS_FOUND);
-	BUG_ON(ac->ac_b_ex.fe_len <= 0);
 
 	sb = ac->ac_sb;
 	sbi = EXT4_SB(sb);
@@ -3062,13 +3175,14 @@ static void ext4_mb_normalize_group_request(struct ext4_allocation_context *ac)
 				struct ext4_allocation_request *ar)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
-	int bsbits, max;
+	int bsbits, i, wind;
 	ext4_lblk_t end;
-	loff_t size, start_off;
+	loff_t size;
 	loff_t orig_size __maybe_unused;
 	ext4_lblk_t start;
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
 	struct ext4_prealloc_space *pa;
+	unsigned long value, last_non_zero;
 
 	/* do normalize only data requests, metadata requests
 	   do not need preallocation */
@@ -3097,51 +3211,47 @@ static void ext4_mb_normalize_group_request(struct ext4_allocation_context *ac)
 	size = size << bsbits;
 	if (size < i_size_read(ac->ac_inode))
 		size = i_size_read(ac->ac_inode);
-	orig_size = size;
+	size = (size + ac->ac_sb->s_blocksize - 1) >> bsbits;
 
-	/* max size of free chunks */
-	max = 2 << bsbits;
-
-#define NRL_CHECK_SIZE(req, size, max, chunk_size)	\
-		(req <= (size) || max <= (chunk_size))
-
-	/* first, try to predict filesize */
-	/* XXX: should this table be tunable? */
-	start_off = 0;
-	if (size <= 16 * 1024) {
-		size = 16 * 1024;
-	} else if (size <= 32 * 1024) {
-		size = 32 * 1024;
-	} else if (size <= 64 * 1024) {
-		size = 64 * 1024;
-	} else if (size <= 128 * 1024) {
-		size = 128 * 1024;
-	} else if (size <= 256 * 1024) {
-		size = 256 * 1024;
-	} else if (size <= 512 * 1024) {
-		size = 512 * 1024;
-	} else if (size <= 1024 * 1024) {
-		size = 1024 * 1024;
-	} else if (NRL_CHECK_SIZE(size, 4 * 1024 * 1024, max, 2 * 1024)) {
-		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
-						(21 - bsbits)) << 21;
-		size = 2 * 1024 * 1024;
-	} else if (NRL_CHECK_SIZE(size, 8 * 1024 * 1024, max, 4 * 1024)) {
-		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
-							(22 - bsbits)) << 22;
-		size = 4 * 1024 * 1024;
-	} else if (NRL_CHECK_SIZE(ac->ac_o_ex.fe_len,
-					(8<<20)>>bsbits, max, 8 * 1024)) {
-		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
-							(23 - bsbits)) << 23;
-		size = 8 * 1024 * 1024;
+	start = wind = 0;
+	value = last_non_zero = 0;
+
+	/* let's choose preallocation window depending on file size */
+	for (i = 0; i < EXT4_MAX_PREALLOC_TABLE; i++) {
+		value = sbi->s_mb_prealloc_table[i];
+		if (value == 0)
+			break;
+		else
+			last_non_zero = value;
+
+		if (size <= value) {
+			wind = value;
+			break;
+		}
+	}
+
+	if (wind == 0) {
+		if (last_non_zero != 0) {
+			u64 tstart, tend;
+
+			/* file is quite large, we now preallocate with
+			 * the biggest configured window with regart to
+			 * logical offset
+			 */
+			wind = last_non_zero;
+			tstart = ac->ac_o_ex.fe_logical;
+			do_div(tstart, wind);
+			start = tstart * wind;
+			tend = ac->ac_o_ex.fe_logical + ac->ac_o_ex.fe_len - 1;
+			do_div(tend, wind);
+			tend = tend * wind + wind;
+			size = tend - start;
+		}
 	} else {
-		start_off = (loff_t) ac->ac_o_ex.fe_logical << bsbits;
-		size	  = (loff_t) EXT4_C2B(EXT4_SB(ac->ac_sb),
-					      ac->ac_o_ex.fe_len) << bsbits;
+		size = wind;
 	}
-	size = size >> bsbits;
-	start = start_off >> bsbits;
+
+	orig_size = size;
 
 	/* don't cover already allocated blocks in selected range */
 	if (ar->pleft && start <= ar->lleft) {
@@ -3223,7 +3333,6 @@ static void ext4_mb_normalize_group_request(struct ext4_allocation_context *ac)
 			 (unsigned long) ac->ac_o_ex.fe_logical);
 		BUG();
 	}
-	BUG_ON(size <= 0 || size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
 
 	/* now prepare goal request */
 
@@ -4191,11 +4300,19 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
 
 	/* don't use group allocation for large files */
 	size = max(size, isize);
-	if (size > sbi->s_mb_stream_request) {
+	if ((ac->ac_o_ex.fe_len >= sbi->s_mb_small_req) ||
+	    (size >= sbi->s_mb_large_req)) {
 		ac->ac_flags |= EXT4_MB_STREAM_ALLOC;
 		return;
 	}
 
+	/*
+	 * request is so large that we don't care about
+	 * streaming - it overweights any possible seek
+	 */
+	if (ac->ac_o_ex.fe_len >= sbi->s_mb_large_req)
+		return;
+
 	BUG_ON(ac->ac_lg != NULL);
 	/*
 	 * locality group prealloc space are per cpu. The reason for having
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index a616f58..a52b311 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -752,8 +752,8 @@ struct stats dx_show_entries(struct dx_hash_info *hinfo, struct inode *dir,
 	if (root->info.hash_version != DX_HASH_TEA &&
 	    root->info.hash_version != DX_HASH_HALF_MD4 &&
 	    root->info.hash_version != DX_HASH_LEGACY) {
-		ext4_warning_inode(dir, "Unrecognised inode hash code %u",
-				   root->info.hash_version);
+		ext4_warning_inode(dir, "Unrecognised inode hash code %u for directory %lu",
+				   root->info.hash_version, dir->i_ino);
 		goto fail;
 	}
 	if (fname)
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 04b4f53..1375815 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -184,7 +184,8 @@ static ssize_t journal_task_show(struct ext4_sb_info *sbi, char *buf)
 EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
 EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
 EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
-EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
+EXT4_RW_ATTR_SBI_UI(mb_small_req, s_mb_small_req);
+EXT4_RW_ATTR_SBI_UI(mb_large_req, s_mb_large_req);
 EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
 EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
 EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
@@ -213,7 +214,8 @@ static ssize_t journal_task_show(struct ext4_sb_info *sbi, char *buf)
 	ATTR_LIST(mb_max_to_scan),
 	ATTR_LIST(mb_min_to_scan),
 	ATTR_LIST(mb_order2_req),
-	ATTR_LIST(mb_stream_req),
+	ATTR_LIST(mb_small_req),
+	ATTR_LIST(mb_large_req),
 	ATTR_LIST(mb_group_prealloc),
 	ATTR_LIST(max_writeback_mb_bump),
 	ATTR_LIST(extent_max_zeroout_kb),
@@ -413,6 +415,8 @@ int ext4_register_sysfs(struct super_block *sb)
 				sb);
 		proc_create_seq_data("mb_groups", S_IRUGO, sbi->s_proc,
 				&ext4_mb_seq_groups_ops, sb);
+		proc_create_data("prealloc_table", S_IRUGO, sbi->s_proc,
+				 &ext4_seq_prealloc_table_fops, sb);
 	}
 	return 0;
 }
-- 
1.8.3.1