From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
Date: Tue, 25 Feb 2014 12:29:16 +0000
Subject: Ideas/suggestions to avoid repeated locking and reducing too
 many lists with dmaengine?
In-Reply-To: <530BC9F8.2040402@ti.com>
References: <530B9784.5060904@ti.com>
 <20140224192152.GV27282@n2100.arm.linux.org.uk> <530BC9F8.2040402@ti.com>
Message-ID: <20140225122916.GX27282@n2100.arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Feb 24, 2014 at 04:38:48PM -0600, Joel Fernandes wrote:
> Actually I did do some tracing earlier before I posted this thread- and
> notice there was excessive traces of locking/unlocking. It is very light
> though as you pointed and lighter without debug options. The only other
> notable difference is the fact that we are now going through the dmaengine
> framework in the newer kernel vs the faster one.

Okay, for OMAP, there's additional latency caused by the tasklet which
starts a transaction when there's no previous transaction running -
that will be your biggest problem.

I do want to move omap-dma away from having a fixed binding between
claimed channels and the logical channels since that's too wasteful,
and that's what the tasklet will eventually be doing - but with
omap-dma being divorsed from the old code, this tasklet may not be
necessary anymore (since we no longer have to operate in process
context for that bit.)

There's a huge pile of patches I have queued up for the next merge
window in linux-next - I'd rather get these into mainline before
trying to do any restructuring, otherwise we're going to get into
a hell of a problem with merge conflicts.

-- 
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