From: Dave Chinner <david@fromorbit.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: Zheng Liu <gnehzuil.liu@gmail.com>,
linux-ext4@vger.kernel.org, Zheng Liu <wenqing.lz@taobao.com>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Jan Kara <jack@suse.cz>
Subject: Re: [RFC PATCH v2 0/4] ext4: extents status tree shrinker improvement
Date: Tue, 22 Apr 2014 09:10:02 +1000 [thread overview]
Message-ID: <20140421231002.GC15995@dastard> (raw)
In-Reply-To: <20140417153526.GF18591@thunk.org>
On Thu, Apr 17, 2014 at 11:35:26AM -0400, Theodore Ts'o wrote:
> So I've been thinking about this some more, and it seems to me is
> actually, what we need is *both* an LRU and a RR scheme.
We already have shrinker implementations that do this. It would
probably take 10-15 lines of code to add it to any existing LRU
list based shrinker.....
> The real problem here is that we have workloads that are generating a
> large number of "low value" extent cache entries. That is, they are
> extremely unlikely to be used again, because they are small, and being
> generated when you have a highly fragmented extent status cache, and
> very often, the workload is a random read/write workload, so there is
> no way the full "working set" of extent cache entries could be kept in
> memory at the same time anyway. These less valuable cache entries are
> being generated at a very high rate, and we want to make sure we don't
> penalize the "valuable" cache entries.
Yup, an "object referenced" bit that gets set on a cache lookup hit.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2014-04-21 23:10 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-16 11:30 [RFC PATCH v2 0/4] ext4: extents status tree shrinker improvement Zheng Liu
2014-04-16 11:30 ` [RFC PATCH v2 1/4] ext4: improve extents status tree trace point Zheng Liu
2014-04-16 11:30 ` [RFC PATCH v2 2/4] ext4: track extent status tree shrinker delay statictics Zheng Liu
2014-04-16 11:30 ` [RFC PATCH v2 3/4] ext4: improve extents status tree shrinker lru algorithm Zheng Liu
2014-04-16 11:30 ` [RFC PATCH v2 4/4] ext4: use a round-robin algorithm to shrink extent cache Zheng Liu
2014-04-16 15:19 ` [RFC PATCH v2 0/4] ext4: extents status tree shrinker improvement Theodore Ts'o
2014-04-16 15:42 ` Theodore Ts'o
2014-04-17 15:35 ` Theodore Ts'o
2014-04-21 13:50 ` Zheng Liu
2014-04-21 14:05 ` Theodore Ts'o
2014-04-21 14:46 ` Zheng Liu
2014-04-21 14:54 ` Theodore Ts'o
2014-04-21 23:10 ` Dave Chinner [this message]
2014-04-23 5:35 ` Zheng Liu
2014-04-24 1:46 ` Dave Chinner
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