netdev - Re: [PATCH 4/4] bgmac: fix DMA rx corruption

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Message-ID: <1428859488.25985.347.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Sun, 12 Apr 2015 10:24:48 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Felix Fietkau <nbd@...nwrt.org>
Cc:	netdev@...r.kernel.org, zajec5@...il.com, hauke@...ke-m.de
Subject: Re: [PATCH 4/4] bgmac: fix DMA rx corruption

On Sun, 2015-04-12 at 12:43 +0200, Felix Fietkau wrote:
> On 2015-04-12 12:31, Eric Dumazet wrote:

> > This might be better for performance to perform one single bgmac_write()
> > at the end of bgmac_dma_rx_read(), and leave this one in place as well,
> > not for performance since this is slow path, but correctness.
> I intentionally made it write this field for every slot update, because
> it might potentially allow the hardware to push frames faster when under
> pressure. The CPU isn't fast enough to handle gigabit speeds anyway.

If CPU is not fast enough, then it makes sense to optimize this part,
and save cpu cycles for actual processing.

You know, even a fast cpu is not able to keep up at 40Gbits.

You have a clear opportunity to have batching right there, take it.


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