From: Nick Piggin <npiggin@kernel.dk>
To: Dave Chinner <david@fromorbit.com>
Cc: Nick Piggin <npiggin@kernel.dk>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Inode Lock Scalability V4
Date: Sun, 17 Oct 2010 13:55:33 +1100 [thread overview]
Message-ID: <20101017025533.GA6482@amd> (raw)
In-Reply-To: <20101017024759.GI32255@dastard>
On Sun, Oct 17, 2010 at 01:47:59PM +1100, Dave Chinner wrote:
> On Sun, Oct 17, 2010 at 04:55:15AM +1100, Nick Piggin wrote:
> > On Sat, Oct 16, 2010 at 07:13:54PM +1100, Dave Chinner wrote:
> > > This patch set is just the basic inode_lock breakup patches plus a
> > > few more simple changes to the inode code. It stops short of
> > > introducing RCU inode freeing because those changes are not
> > > completely baked yet.
> >
> > It also doesn't contain per-zone locking and lrus, or scalability of
> > superblock list locking.
>
> Sure - that's all explained in the description of what the series
> actually contains later on.
>
> > And while the rcu-walk path walking is not fully baked, it has been
> > reviewed by Linus and is in pretty good shape. So I prefer to utilise
> > RCU locking here too, seeing as we know it will go in.
>
> I deliberately left out the RCU changes as we know that the version
> that is in your tree causes siginificant performance regressions for
> single threaded and some parallel workloads on small (<=8p)
> machines.
The worst-case microbenchmark is not a "significant performance
regression". It is a worst case demonstration. With the parallel
workloads, are you referring to your postmark xfs workload? It was
actually due to lazy LRU, IIRC. I didn't think RCU overhead was
noticable there actually.
Anyway, I've already gone over this couple of months ago when we
were discussing it. We know it could cause some small regressions,
if they are small it is considered acceptable and outweighed
greatly by fastpath speedup. And I have a design to do slab RCU
which can be used if regressions are large. Linus signed off on
this, in fact. Why weren't you debating it then?
> There is more development needed there so, IMO, it has
> never been a candidate for this series which is aimed directly at
> .37 inclusion.
next prev parent reply other threads:[~2010-10-17 2:55 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-16 8:13 Inode Lock Scalability V4 Dave Chinner
2010-10-16 8:13 ` [PATCH 01/19] fs: switch bdev inode bdi's correctly Dave Chinner
2010-10-16 9:30 ` Nick Piggin
2010-10-16 16:31 ` Christoph Hellwig
2010-10-16 8:13 ` [PATCH 02/19] kernel: add bl_list Dave Chinner
2010-10-16 9:51 ` Nick Piggin
2010-10-16 16:32 ` Christoph Hellwig
2010-10-16 8:13 ` [PATCH 03/19] fs: Convert nr_inodes and nr_unused to per-cpu counters Dave Chinner
2010-10-16 8:29 ` Eric Dumazet
2010-10-16 10:04 ` Dave Chinner
2010-10-16 10:27 ` Eric Dumazet
2010-10-16 17:26 ` Peter Zijlstra
2010-10-17 1:09 ` Dave Chinner
2010-10-17 1:12 ` Christoph Hellwig
2010-10-17 2:16 ` Dave Chinner
2010-10-16 8:13 ` [PATCH 04/19] fs: Implement lazy LRU updates for inodes Dave Chinner
2010-10-16 9:29 ` Nick Piggin
2010-10-16 16:59 ` Christoph Hellwig
2010-10-16 17:29 ` Nick Piggin
2010-10-16 17:34 ` Nick Piggin
2010-10-17 0:47 ` Christoph Hellwig
2010-10-17 0:47 ` Christoph Hellwig
2010-10-17 2:09 ` Nick Piggin
2010-10-17 1:53 ` Dave Chinner
2010-10-16 8:13 ` [PATCH 05/19] fs: inode split IO and LRU lists Dave Chinner
2010-10-16 8:14 ` [PATCH 06/19] fs: Clean up inode reference counting Dave Chinner
2010-10-16 8:14 ` [PATCH 07/19] exofs: use iput() for inode reference count decrements Dave Chinner
2010-10-16 8:14 ` [PATCH 08/19] fs: rework icount to be a locked variable Dave Chinner
2010-10-16 8:14 ` [PATCH 09/19] fs: Factor inode hash operations into functions Dave Chinner
2010-10-16 8:14 ` [PATCH 10/19] fs: Introduce per-bucket inode hash locks Dave Chinner
2010-10-16 8:14 ` [PATCH 11/19] fs: add a per-superblock lock for the inode list Dave Chinner
2010-10-16 8:14 ` [PATCH 12/19] fs: split locking of inode writeback and LRU lists Dave Chinner
2010-10-16 8:14 ` [PATCH 13/19] fs: Protect inode->i_state with the inode->i_lock Dave Chinner
2010-10-16 8:14 ` [PATCH 14/19] fs: introduce a per-cpu last_ino allocator Dave Chinner
2010-10-16 8:14 ` [PATCH 15/19] fs: Make iunique independent of inode_lock Dave Chinner
2010-10-16 8:14 ` [PATCH 16/19] fs: icache remove inode_lock Dave Chinner
2010-10-16 8:14 ` [PATCH 17/19] fs: Reduce inode I_FREEING and factor inode disposal Dave Chinner
2010-10-17 1:30 ` Christoph Hellwig
2010-10-17 2:49 ` Nick Piggin
2010-10-17 4:13 ` Dave Chinner
2010-10-17 4:35 ` Nick Piggin
2010-10-17 5:13 ` Nick Piggin
2010-10-17 6:52 ` Dave Chinner
2010-10-17 7:05 ` Nick Piggin
2010-10-17 23:39 ` Dave Chinner
2010-10-18 21:27 ` Sage Weil
2010-10-19 3:54 ` Nick Piggin
2010-10-16 8:14 ` [PATCH 18/19] fs: split __inode_add_to_list Dave Chinner
2010-10-16 8:14 ` [PATCH 19/19] fs: do not assign default i_ino in new_inode Dave Chinner
2010-10-16 9:09 ` Eric Dumazet
2010-10-16 16:35 ` Christoph Hellwig
2010-10-18 9:11 ` Eric Dumazet
2010-10-18 14:48 ` Christoph Hellwig
2010-10-16 17:55 ` Inode Lock Scalability V4 Nick Piggin
2010-10-17 2:47 ` Dave Chinner
2010-10-17 2:55 ` Nick Piggin [this message]
2010-10-17 2:57 ` Nick Piggin
2010-10-17 6:10 ` Dave Chinner
2010-10-17 6:34 ` Nick Piggin
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