From: Theodore Ts'o Subject: [PATCH] ext4: Make the length of the mb_history file tunable Date: Fri, 1 May 2009 20:31:37 -0400 Message-ID: <1241224297-11223-1-git-send-email-tytso@mit.edu> References: <6601abe90904201153q5e66cb30na22a49767245e53f@mail.gmail.com> Cc: Michael Rubin , Ext4 Developers List , Curt Wohlgemuth , "Theodore Ts'o" To: Curt Wohlgemuth Return-path: Received: from THUNK.ORG ([69.25.196.29]:42589 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751604AbZEBAbl (ORCPT ); Fri, 1 May 2009 20:31:41 -0400 In-Reply-To: <6601abe90904201153q5e66cb30na22a49767245e53f@mail.gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Curt Wohlgemuth In memory-constrained systems with many partitions, the ~68K for each partition for the mb_history buffer can be excessive. This patch adds a new mount option, mb_history_length, as well as a way of setting the default via a module parameter (or via a sysfs parameter in /sys/module/ext4/parameter/default_mb_history_length). If the mb_history_length is set to zero, the mb_history facility is disabled entirely. Signed-off-by: Curt Wohlgemuth Signed-off-by: "Theodore Ts'o" --- I completely revamped how how tunable is set. The combination of a mount option plus a default which can be tuned via a sysfs file or a module parameter is cleaner, and certainly requires less code. (No need to open-code new file in /proc, which should be avoided if at all possible.) Anyway, this is what I've dropped into the ext4 patch queue. fs/ext4/mballoc.c | 13 +++++++------ fs/ext4/super.c | 18 +++++++++++++++++- 2 files changed, 24 insertions(+), 7 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index dbd47ea..df75855 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2413,7 +2413,8 @@ static void ext4_mb_history_release(struct super_block *sb) if (sbi->s_proc != NULL) { remove_proc_entry("mb_groups", sbi->s_proc); - remove_proc_entry("mb_history", sbi->s_proc); + if (sbi->s_mb_history_max) + remove_proc_entry("mb_history", sbi->s_proc); } kfree(sbi->s_mb_history); } @@ -2424,17 +2425,17 @@ static void ext4_mb_history_init(struct super_block *sb) int i; if (sbi->s_proc != NULL) { - proc_create_data("mb_history", S_IRUGO, sbi->s_proc, - &ext4_mb_seq_history_fops, sb); + if (sbi->s_mb_history_max) + proc_create_data("mb_history", S_IRUGO, sbi->s_proc, + &ext4_mb_seq_history_fops, sb); proc_create_data("mb_groups", S_IRUGO, sbi->s_proc, &ext4_mb_seq_groups_fops, sb); } - sbi->s_mb_history_max = 1000; sbi->s_mb_history_cur = 0; spin_lock_init(&sbi->s_mb_history_lock); i = sbi->s_mb_history_max * sizeof(struct ext4_mb_history); - sbi->s_mb_history = kzalloc(i, GFP_KERNEL); + sbi->s_mb_history = i ? kzalloc(i, GFP_KERNEL) : NULL; /* if we can't allocate history, then we simple won't use it */ } @@ -2444,7 +2445,7 @@ ext4_mb_store_history(struct ext4_allocation_context *ac) struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); struct ext4_mb_history h; - if (unlikely(sbi->s_mb_history == NULL)) + if (sbi->s_mb_history == NULL) return; if (!(ac->ac_op & sbi->s_mb_history_filter)) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 7903f20..39223a5 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -47,6 +47,13 @@ #include "xattr.h" #include "acl.h" +static int default_mb_history_length = 1000; + +module_param_named(default_mb_history_length, default_mb_history_length, + int, 0644); +MODULE_PARM_DESC(default_mb_history_length, + "Default number of entries saved for mb_history"); + struct proc_dir_entry *ext4_proc_root; static struct kset *ext4_kset; @@ -1042,7 +1049,7 @@ enum { Opt_journal_update, Opt_journal_dev, Opt_journal_checksum, Opt_journal_async_commit, Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback, - Opt_data_err_abort, Opt_data_err_ignore, + Opt_data_err_abort, Opt_data_err_ignore, Opt_mb_history_length, Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota, Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota, Opt_ignore, Opt_barrier, Opt_nobarrier, Opt_err, Opt_resize, @@ -1088,6 +1095,7 @@ static const match_table_t tokens = { {Opt_data_writeback, "data=writeback"}, {Opt_data_err_abort, "data_err=abort"}, {Opt_data_err_ignore, "data_err=ignore"}, + {Opt_mb_history_length, "mb_history_length=%u"}, {Opt_offusrjquota, "usrjquota="}, {Opt_usrjquota, "usrjquota=%s"}, {Opt_offgrpjquota, "grpjquota="}, @@ -1329,6 +1337,13 @@ static int parse_options(char *options, struct super_block *sb, case Opt_data_err_ignore: clear_opt(sbi->s_mount_opt, DATA_ERR_ABORT); break; + case Opt_mb_history_length: + if (match_int(&args[0], &option)) + return 0; + if (option < 0) + return 0; + sbi->s_mb_history_max = option; + break; #ifdef CONFIG_QUOTA case Opt_usrjquota: qtype = USRQUOTA; @@ -2345,6 +2360,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) sbi->s_commit_interval = JBD2_DEFAULT_MAX_COMMIT_AGE * HZ; sbi->s_min_batch_time = EXT4_DEF_MIN_BATCH_TIME; sbi->s_max_batch_time = EXT4_DEF_MAX_BATCH_TIME; + sbi->s_mb_history_max = default_mb_history_length; set_opt(sbi->s_mount_opt, BARRIER); -- 1.6.0.4