Date: Sat, 12 Dec 2009 13:24:43 +0100
From: Jens Axboe <jens.axboe@oracle.com>
To: Matthew Garrett <mjg@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] laptop-mode: Make flushes per-device
Message-ID: <20091212122443.GA8742@kernel.dk>
References: <20091211164433.GA1980@srcf.ucam.org> <1260554071-2190-1-git-send-email-mjg@redhat.com>
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On Fri, Dec 11 2009, Matthew Garrett wrote:
> One of the features of laptop-mode is that it forces a writeout of dirty
> pages if something else triggers a physical read or write from a device.
> The current implementation flushes pages on all devices, rather than only
> the one that triggered the flush. This patch alters the behaviour so that
> only the recently accessed block device is flushed, preventing other
> disks being spun up for no terribly good reason.
> 
> Signed-off-by: Matthew Garrett <mjg@redhat.com>
> ---
> 
> The forward struct declaration in writeback.h seems messy, but I'm not
> sure there's a cleaner way to do this. I'm also still woefully
> unfamiliar with the block layer - I /think/ this does the right thing,
> but some review would be nice.

That's because it is messy, why are you passing the request in? It
would be a lot more sane to pass in the queue, better still the backing
device.

What guarentees that the timer isn't running when the bdi goes away?

-- 
Jens Axboe

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