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ext4: add cond_resched() to ext4_free_blocks() & ext4_mb_regular_allocator()

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For a file systems with a very large number of block groups, if all of
the block group bitmaps are in memory and the file system is
relatively badly fragmented, it's possible ext4_mb_regular_allocator()
to take a long time trying to find a good match.  This is especially
true if the tuning parameter mb_max_to_scan has been sent to a very
large number.  So add a cond_resched() to avoid soft lockup warnings
and to provide better system responsiveness.

For ext4_free_blocks(), if we are deleting a large range of blocks,
and data=journal is enabled so that EXT4_FREE_BLOCKS_FORGET is passed,
the loop to call sb_find_get_block() and to call ext4_forget() can
take over 10-15 milliseocnds or more.  So it's better to add a
cond_resched() here a well.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2013-06-12 11:43:02 -04:00
parent 20970ba65d
commit 2ed5724d5a
1 changed files with 3 additions and 1 deletions
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4
fs/ext4/mballoc.c
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@ -2105,6 +2105,7 @@ repeat:
group = ac->ac_g_ex.fe_group;
for (i = 0; i < ngroups; group++, i++) {
cond_resched();
/*
* Artificially restricted ngroups for non-extent
* files makes group > ngroups possible on first loop.
@ -4612,10 +4613,11 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
BUG_ON(bh && (count > 1));
for (i = 0; i < count; i++) {
cond_resched();
if (!bh)
tbh = sb_find_get_block(inode->i_sb,
block + i);
if (unlikely(!tbh))
if (!tbh)
continue;
ext4_forget(handle, flags & EXT4_FREE_BLOCKS_METADATA,
inode, tbh, block + i);