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List:       linux-kernel
Subject:    Re: [PATCH 1/9] [I/OAT] DMA memcpy subsystem
From:       "Andrew Grover" <andy.grover () gmail ! com>
Date:       2006-03-31 20:27:31
Message-ID: c0a09e5c0603311227r210209c3v19d80386ab9fc168 () mail ! gmail ! com
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On 3/31/06, Kumar Gala <galak@kernel.crashing.org> wrote:
> > Currently the code updates these variables (kept per cpu) every time a
> > copy is queued. See include/linux/dmaengine.h.
>
> Might it be better to update when the transfer is done incase of an
> error?

The queueing function is really in the best position to do this. It
knows the size of each request. However in the cleanup/status check
routine, all we know is the last request completed -- we don't know
the completed requests' sizes.

The other reason is that the DMA engine should never throw an error.
If it does then something is very wrong, we print scary warnings, and
up-to-date stats are the least of our problems.

Regards -- Andy
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