linux-kernel - Re: [PATCH] virtio_ring: Update weak barriers to use dma

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Message-ID: <871tjs1xle.fsf@rustcorp.com.au>
Date:	Fri, 10 Apr 2015 12:47:01 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Alexander Duyck <alexander.h.duyck@...hat.com>,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Cc:	mst@...hat.com
Subject: Re: [PATCH] virtio_ring: Update weak barriers to use dma_wmb/rmb

Alexander Duyck <alexander.h.duyck@...hat.com> writes:
> This change makes it so that instead of using smp_wmb/rmb which varies
> depending on the kernel configuration we can can use dma_wmb/rmb which for
> most architectures should be equal to or slightly more strict than
> smp_wmb/rmb.
>
> The advantage to this is that these barriers are available to uniprocessor
> builds as well so the performance should improve under such a
> configuration.
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>

This seems OK to me, since it's really as much a cleanup as anything,
but like you I do wonder if there benefit on ARM in practice.

Applied, thanks.

Cheers,
Rusty.
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