From: Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [PATCH, RFC] vm: Add an tuning knob for vm.max_writeback_pages
Date: Mon, 31 Aug 2009 22:36:36 +0200
Message-ID: <20090831203636.GD12579@kernel.dk>
References: <1251600858-21294-1-git-send-email-tytso@mit.edu> <20090830165229.GA5189@infradead.org> <20090830181731.GA20822@mit.edu> <20090830222710.GA9938@infradead.org> <20090831030815.GD20822@mit.edu> <20090831102909.GS12579@kernel.dk> <20090831104748.GT12579@kernel.dk> <20090831155441.GB23535@mit.edu>
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Cc: Christoph Hellwig <hch@infradead.org>, linux-mm@kvack.org,
	Ext4 Developers List <linux-ext4@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, chris.mason@oracle.com
To: Theodore Tso <tytso@mit.edu>
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On Mon, Aug 31 2009, Theodore Tso wrote:
> At the risk of asking a stupid question, what *is* range_cyclic and
> what is it trying to do?  I've been looking at the code and am I'm
> getting myself very confused about what the code is trying to do and
> what was its original intent.

Range cyclic means that the current writeback in ->writepages() should
start where it left off the last time, non-range cyclic starts off at
->range_start. ->writepages() can use mapping->writeback_index to store
such information.

-- 
Jens Axboe

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