linux-kernel - Re: [PATCH 0/4] dcache: make Oracle more scalable on large systems

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Message-ID: <m2bobdxl1i.fsf@firstfloor.org>
Date:	Thu, 21 Feb 2013 16:13:45 -0800
From:	Andi Kleen <andi@...stfloor.org>
To:	Dave Chinner <david@...morbit.com>
Cc:	Waiman Long <Waiman.Long@...com>, linux-fsdevel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] dcache: make Oracle more scalable on large systems

Dave Chinner <david@...morbit.com> writes:

> On Tue, Feb 19, 2013 at 01:50:55PM -0500, Waiman Long wrote:
>> It was found that the Oracle database software issues a lot of call
>> to the seq_path() kernel function which translates a (dentry, mnt)
>> pair to an absolute path. The seq_path() function will eventually
>> take the following two locks:
>
> Nobody should be doing reverse dentry-to-name lookups in a quantity
> sufficient for it to become a performance limiting factor. What is
> the Oracle DB actually using this path for?

Yes calling d_path frequently is usually a bug elsewhere.
Is that through /proc ? 

-Andi


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