From: Mel Gorman <mgorman@suse.de>
To: Glauber Costa <glommer@openvz.org>
Cc: linux-mm@kvack.org, cgroups@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Greg Thelen <gthelen@google.com>,
kamezawa.hiroyu@jp.fujitsu.com, Michal Hocko <mhocko@suse.cz>,
Johannes Weiner <hannes@cmpxchg.org>,
Dave Chinner <dchinner@redhat.com>
Subject: Re: [PATCH v4 04/31] dentry: move to per-sb LRU locks
Date: Tue, 30 Apr 2013 15:01:44 +0100 [thread overview]
Message-ID: <20130430140144.GD6415@suse.de> (raw)
In-Reply-To: <1367018367-11278-5-git-send-email-glommer@openvz.org>
On Sat, Apr 27, 2013 at 03:19:00AM +0400, Glauber Costa wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> With the dentry LRUs being per-sb structures, there is no real need
> for a global dentry_lru_lock. The locking can be made more
> fine-grained by moving to a per-sb LRU lock, isolating the LRU
> operations of different filesytsems completely from each other.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mel Gorman <mgorman@suse.de>
But one comment below
> @@ -81,7 +81,6 @@
> int sysctl_vfs_cache_pressure __read_mostly = 100;
> EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
>
> -static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
> __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
>
> EXPORT_SYMBOL(rename_lock);
It made sense to cache-align these locks because you don't want two
unrelated global locks causing each other to bounce but ....
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 8d47c9a..df3174d 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1263,7 +1263,9 @@ struct super_block {
> struct list_head s_files;
> #endif
> struct list_head s_mounts; /* list of mounts; _not_ for fs use */
> - /* s_dentry_lru, s_nr_dentry_unused protected by dcache.c lru locks */
> +
> + /* s_dentry_lru_lock protects s_dentry_lru and s_nr_dentry_unused */
> + spinlock_t s_dentry_lru_lock ____cacheline_aligned_in_smp;
> struct list_head s_dentry_lru; /* unused dentry lru */
> int s_nr_dentry_unused; /* # of dentry on lru */
>
It's less compelling to align within a structure like this. If move the
lock and the fields it protects to a read-mostly section then there
should be no need to cache-align the lock, create a large hole in the
struct and grow the size of struct super_block unnecessarily.
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2013-04-30 14:01 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-26 23:18 [PATCH v4 00/31] kmemcg shrinkers Glauber Costa
2013-04-26 23:18 ` [PATCH v4 01/31] super: fix calculation of shrinkable objects for small numbers Glauber Costa
2013-04-30 13:03 ` Mel Gorman
2013-04-26 23:18 ` [PATCH v4 02/31] vmscan: take at least one pass with shrinkers Glauber Costa
2013-04-30 13:22 ` Mel Gorman
2013-04-30 13:31 ` Glauber Costa
2013-04-30 15:37 ` Mel Gorman
2013-05-07 13:35 ` Glauber Costa
2013-04-26 23:18 ` [PATCH v4 03/31] dcache: convert dentry_stat.nr_unused to per-cpu counters Glauber Costa
2013-04-30 13:37 ` Mel Gorman
2013-04-26 23:19 ` [PATCH v4 04/31] dentry: move to per-sb LRU locks Glauber Costa
2013-04-30 14:01 ` Mel Gorman [this message]
2013-04-26 23:19 ` [PATCH v4 05/31] dcache: remove dentries from LRU before putting on dispose list Glauber Costa
2013-04-30 14:14 ` Mel Gorman
2013-04-26 23:19 ` [PATCH v4 06/31] mm: new shrinker API Glauber Costa
2013-04-30 14:40 ` Mel Gorman
2013-04-30 15:03 ` Glauber Costa
2013-04-30 15:32 ` Mel Gorman
2013-04-26 23:19 ` [PATCH v4 07/31] shrinker: convert superblock shrinkers to new API Glauber Costa
2013-04-30 14:49 ` Mel Gorman
2013-04-26 23:19 ` [PATCH v4 08/31] list: add a new LRU list type Glauber Costa
2013-04-30 15:18 ` Mel Gorman
2013-04-30 16:01 ` Glauber Costa
2013-04-26 23:19 ` [PATCH v4 09/31] inode: convert inode lru list to generic lru list code Glauber Costa
2013-04-30 15:46 ` Mel Gorman
2013-05-07 13:47 ` Glauber Costa
2013-04-26 23:19 ` [PATCH v4 10/31] dcache: convert to use new lru list infrastructure Glauber Costa
2013-04-30 16:04 ` Mel Gorman
2013-04-30 16:13 ` Glauber Costa
2013-04-26 23:19 ` [PATCH v4 11/31] list_lru: per-node " Glauber Costa
2013-04-30 16:33 ` Mel Gorman
2013-04-30 21:44 ` Glauber Costa
2013-04-26 23:19 ` [PATCH v4 12/31] shrinker: add node awareness Glauber Costa
2013-04-30 16:35 ` Mel Gorman
2013-04-26 23:19 ` [PATCH v4 13/31] fs: convert inode and dentry shrinking to be node aware Glauber Costa
2013-04-30 17:39 ` Mel Gorman
2013-04-26 23:19 ` [PATCH v4 14/31] xfs: convert buftarg LRU to generic code Glauber Costa
2013-04-26 23:19 ` [PATCH v4 15/31] xfs: convert dquot cache lru to list_lru Glauber Costa
2013-04-26 23:19 ` [PATCH v4 16/31] fs: convert fs shrinkers to new scan/count API Glauber Costa
2013-04-26 23:19 ` [PATCH v4 17/31] drivers: convert shrinkers to new count/scan API Glauber Costa
2013-04-30 21:53 ` Mel Gorman
2013-04-30 22:00 ` Kent Overstreet
2013-05-02 9:37 ` Mel Gorman
2013-05-02 13:37 ` Glauber Costa
2013-05-01 15:26 ` Daniel Vetter
2013-05-02 9:31 ` Mel Gorman
2013-04-26 23:19 ` [PATCH v4 18/31] shrinker: convert remaining shrinkers to " Glauber Costa
2013-04-26 23:19 ` [PATCH v4 19/31] hugepage: convert huge zero page shrinker to new shrinker API Glauber Costa
2013-04-26 23:19 ` [PATCH v4 20/31] shrinker: Kill old ->shrink API Glauber Costa
2013-04-30 21:57 ` Mel Gorman
2013-04-26 23:19 ` [PATCH v4 21/31] vmscan: also shrink slab in memcg pressure Glauber Costa
2013-04-26 23:19 ` [PATCH v4 22/31] memcg,list_lru: duplicate LRUs upon kmemcg creation Glauber Costa
2013-04-26 23:19 ` [PATCH v4 23/31] lru: add an element to a memcg list Glauber Costa
2013-04-26 23:19 ` [PATCH v4 24/31] list_lru: per-memcg walks Glauber Costa
2013-04-26 23:19 ` [PATCH v4 25/31] memcg: per-memcg kmem shrinking Glauber Costa
2013-04-26 23:19 ` [PATCH v4 26/31] memcg: scan cache objects hierarchically Glauber Costa
2013-04-26 23:19 ` [PATCH v4 27/31] super: targeted memcg reclaim Glauber Costa
2013-04-26 23:19 ` [PATCH v4 28/31] memcg: move initialization to memcg creation Glauber Costa
2013-04-26 23:19 ` [PATCH v4 29/31] vmpressure: in-kernel notifications Glauber Costa
2013-04-26 23:19 ` [PATCH v4 30/31] memcg: reap dead memcgs upon global memory pressure Glauber Costa
2013-04-26 23:19 ` [PATCH v4 31/31] memcg: debugging facility to access dangling memcgs Glauber Costa
2013-04-30 22:47 ` [PATCH v4 00/31] kmemcg shrinkers Mel Gorman
2013-05-01 9:05 ` Mel Gorman
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