From: Nick Piggin <npiggin@suse.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [patch 03/33] fs: scale files_lock
Date: Thu, 1 Oct 2009 04:16:57 +0200 [thread overview]
Message-ID: <20091001021657.GO6327@wotan.suse.de> (raw)
In-Reply-To: <1254144248.15795.6.camel@laptop>
On Mon, Sep 28, 2009 at 03:24:08PM +0200, Peter Zijlstra wrote:
> On Fri, 2009-09-04 at 16:51 +1000, npiggin@suse.de wrote:
> > Improve scalability of files_lock by adding per-cpu, per-sb files lists,
> > protected with per-cpu locking. Effectively turning it into a big-writer
> > lock.
>
> What I did was fine-grain locking the double linked list so that you can
> delete items without hitting a global lock.
>
> For addition I added per-cpu list-heads that would be spliced onto the
> global list once in a while.
>
> Granted, the code was a tad involved... and hch wanted to get rid of
> these lists, which is of course a much better solution.
I did see that of course, and I sent you a critique of it... I
didn't think it was appropriate for reasons I can't remember off
hand (either overly complex for the same task, or had a scalability
problem).
files_lock I would love to see go away completely, and in fact
depending on progress of work to that end, these patches may never
need to be merged. The problem I have is:
1. I don't want to significantly change data structures or cause
avoidable reductions in potential expressiveness of the data
structures we have. (I don't want someone to complain that my
patches suck because they want to be able to traverse files).
2. I need to take out this lock otherwise it become the choke
point and hides the rest of the progress on the rest of the
scalability work.
Again, I think brlock is not such a terrible thing for contention
especially if we're looking at umount slowpath... For this guy
actually though, the read side can probably be turned into RCU
traversal quite easily, I _think_.
next prev parent reply other threads:[~2009-10-01 2:16 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-04 6:51 [patch 00/33] my current vfs scalability patch queue npiggin
2009-09-04 6:51 ` [patch 01/33] fs: no games with DCACHE_UNHASHED npiggin
2009-09-04 6:51 ` [patch 02/33] fs: cleanup files_lock npiggin
2009-09-04 6:51 ` [patch 03/33] fs: scale files_lock npiggin
2009-09-28 13:22 ` Peter Zijlstra
2009-09-28 13:24 ` Peter Zijlstra
2009-10-01 2:16 ` Nick Piggin [this message]
[not found] ` <r2i3282373b1004011751j440635b3n484018db2e2bc50c@mail.gmail.com>
2010-04-02 2:24 ` [patch 1/2] fs: cleanup files_lock tim
2009-09-04 6:51 ` [patch 04/33] fs: brlock vfsmount_lock npiggin
2009-09-04 15:19 ` Jens Axboe
2009-09-07 7:39 ` Nick Piggin
2009-09-22 15:17 ` Al Viro
2009-09-27 19:56 ` Nick Piggin
2009-09-28 13:21 ` Peter Zijlstra
2009-10-01 2:10 ` Nick Piggin
2009-09-04 6:51 ` [patch 05/33] fs: scale mntget/mntput npiggin
2009-09-07 9:41 ` Nick Piggin
2009-09-04 6:51 ` [patch 06/33] fs: dcache scale hash npiggin
2009-09-04 6:51 ` [patch 07/33] fs: dcache scale lru npiggin
2009-09-04 6:51 ` [patch 08/33] fs: dcache scale nr_dentry npiggin
2009-09-04 14:41 ` Daniel Walker
2009-09-07 7:36 ` Nick Piggin
2009-09-04 6:51 ` [patch 09/33] fs: dcache scale dentry refcount npiggin
2009-09-06 18:01 ` Eric Paris
2009-09-07 7:44 ` Nick Piggin
2009-09-07 11:21 ` Eric Paris
2009-09-07 11:35 ` Nick Piggin
2009-09-04 6:51 ` [patch 10/33] fs: dcache scale d_unhashed npiggin
2009-09-04 6:51 ` [patch 11/33] fs: dcache scale subdirs npiggin
2010-06-17 15:13 ` Peter Zijlstra
2010-06-17 16:53 ` Nick Piggin
2010-06-21 13:35 ` Peter Zijlstra
2010-06-21 14:48 ` Nick Piggin
2010-06-21 14:55 ` Peter Zijlstra
2010-06-22 6:02 ` john stultz
2010-06-22 6:06 ` Nick Piggin
2010-06-22 7:27 ` Peter Zijlstra
2010-06-23 2:03 ` john stultz
2010-06-23 7:23 ` Peter Zijlstra
2009-09-04 6:51 ` [patch 12/33] fs: scale inode alias list npiggin
2009-09-04 6:51 ` [patch 13/33] fs: use RCU / seqlock logic for reverse and multi-step operaitons npiggin
2009-09-04 6:51 ` [patch 14/33] fs: dcache remove dcache_lock npiggin
2009-09-04 6:51 ` [patch 15/33] fs: dcache reduce dput locking npiggin
2009-09-04 6:51 ` [patch 16/33] fs: dcache per-bucket dcache hash locking npiggin
2009-09-04 14:51 ` Daniel Walker
2009-09-07 7:38 ` Nick Piggin
2009-09-04 6:51 ` [patch 17/33] fs: dcache reduce dcache_inode_lock npiggin
2009-09-04 6:51 ` [patch 18/33] fs: dcache per-inode inode alias locking npiggin
2009-09-04 6:52 ` [patch 19/33] fs: icache lock s_inodes list npiggin
2009-09-04 6:52 ` [patch 20/33] fs: icache lock inode hash npiggin
2009-09-04 6:52 ` [patch 21/33] fs: icache lock i_state npiggin
2009-09-04 6:52 ` [patch 22/33] fs: icache lock i_count npiggin
2009-09-04 6:52 ` [patch 23/33] fs: icache atomic inodes_stat npiggin
2009-09-04 6:52 ` [patch 24/33] fs: icache lock lru/writeback lists npiggin
2009-09-04 6:52 ` [patch 25/33] fs: icache protect inode state npiggin
2009-09-04 6:52 ` [patch 26/33] fs: inode atomic last_ino, iunique lock npiggin
2009-09-04 6:52 ` [patch 27/33] fs: icache remove inode_lock npiggin
2009-09-04 6:52 ` [patch 28/33] fs: inode factor hash lock into functions npiggin
2009-09-04 6:52 ` [patch 29/33] Remove the global inode_hash_lock and replace it with per-hash-bucket locks. fs: inode per-bucket inode hash locks npiggin
2009-09-04 7:05 ` Nick Piggin
2009-09-04 6:52 ` [patch 30/33] fs: inode lazy lru npiggin
2009-09-04 6:52 ` [patch 31/33] fs: RCU free inodes npiggin
2009-09-04 6:52 ` [patch 32/33] fs: rcu walk for i_sb_list npiggin
2009-09-04 6:52 ` [patch 33/33] fs: improve scalability of pseudo filesystems npiggin
2009-09-04 7:05 ` [patch 00/33] my current vfs scalability patch queue Nick Piggin
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