From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: [PATCH] ext4: add cond_resched() to ext4_free_blocks() & ext4_mb_regular_allocator() Date: Wed, 12 Jun 2013 11:49:16 -0400 Message-ID: <1371052156-4821-1-git-send-email-tytso@mit.edu> Cc: Theodore Ts'o To: Ext4 Developers List Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:57302 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755183Ab3FLPtT (ORCPT ); Wed, 12 Jun 2013 11:49:19 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: 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" --- fs/ext4/mballoc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index def8408..1a9c22b 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -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); -- 1.7.12.rc0.22.gcdd159b