Date: Thu, 25 May 2006 07:21:17 +1000
From: Anton Blanchard <anton@samba.org>
To: Brice Goglin <brice@myri.com>
Cc: netdev@vger.kernel.org, gallatin@myri.com, linux-kernel@vger.kernel.org,
       benh@kernel.crashing.org
Subject: Re: [PATCH 3/4] myri10ge - Driver core
Message-ID: <20060524212117.GD5938@krispykreme>
References: <20060517220218.GA13411@myri.com> <20060517220608.GD13411@myri.com> <20060523153928.GB5938@krispykreme> <4474138C.2050705@myri.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4474138C.2050705@myri.com>
User-Agent: Mutt/1.5.11+cvs20060403
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 870
Lines: 24

 
Hi,

> We didn't get any ppc64 with PCI-E to run Linux so far. What performance
> drop should we expect with our current code ?

We have seen > 20% improvement on ppc64 running some networking
workloads when forcing 128 byte alignment (instead of 16 byte
alignment). DMA writes have to get cacheline aligned (in power of 2
steps) on some IO chips.

> I am not sure what you mean.
> The only ppc64 with PCI-E that we have seen so far (a G5) couldn't do
> write combining according to Apple.

Im thinking more generally, MTRRs are x86 specific and it would be good
to have a more generic way to enable write combining.

Anton
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/