linux-ext4 - Re: [PATCH v4 0/3] ext4: increase mbcache scalability

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Message-ID: <87fvodcb65.fsf@tassilo.jf.intel.com>
Date:	Fri, 24 Jan 2014 13:38:58 -0800
From:	Andi Kleen <andi@...stfloor.org>
To:	T Makphaibulchoke <tmac@...com>
Cc:	viro@...iv.linux.org.uk, tytso@....edu, adilger.kernel@...ger.ca,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, aswin@...com
Subject: Re: [PATCH v4 0/3] ext4: increase mbcache scalability

T Makphaibulchoke <tmac@...com> writes:

> The patch consists of three parts.
>
> The first part changes the implementation of both the block and hash chains of
> an mb_cache from list_head to hlist_bl_head and also introduces new members,
> including a spinlock to mb_cache_entry, as required by the second part.

spinlock per entry is usually overkill for larger hash tables.

Can you use a second smaller lock table that just has locks and is 
indexed by a subset of the hash key. Most likely a very small 
table is good enough.

Also I would be good to have some data on the additional memory consumption.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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