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Date: Sat, 12 Dec 2015 00:58:51 +0100
From: Andreas Grünbacher <andreas.gruenbacher@...il.com>
To: Jan Kara <jack@...e.cz>
Cc: Ted Tso <tytso@....edu>, linux-ext4@...r.kernel.org,
Laurent GUERBY <laurent@...rby.net>,
Andreas Dilger <adilger@...ger.ca>
Subject: Re: [PATCH 6/6] mbcache2: Use referenced bit instead of LRU
Jan,
2015-12-09 18:57 GMT+01:00 Jan Kara <jack@...e.cz>:
> Currently we maintain perfect LRU list by moving entry to the tail of
> the list when it gets used. However these operations on cache-global
> list are relatively expensive.
>
> In this patch we switch to lazy updates of LRU list. Whenever entry gets
> used, we set a referenced bit in it. When reclaiming entries, we give
> referenced entries another round in the LRU.
>
> In my testing this logic gives about 30% boost to workloads with mostly
> unique xattr blocks (e.g. xattr-bench with 10 files and 10000 unique
> xattr values).
I find it quite confusing that with this patch applied, structs
mb2_cache and mb2_cache_entry still contain fields with "lru" in their
name.
Thanks,
Andreas
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