From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 30A8CB70B1 for ; Mon, 10 Oct 2011 20:24:19 +1100 (EST) Subject: Re: [PATCH] mlx4_en: fix transmit of packages when blue frame is enabled From: Benjamin Herrenschmidt To: Eli Cohen In-Reply-To: <20111010091611.GN2681@mtldesk30> References: <1318145118.29415.371.camel@pasglop> <20111010084726.GM2681@mtldesk30> <1318237284.29415.422.camel@pasglop> <20111010091611.GN2681@mtldesk30> Content-Type: text/plain; charset="UTF-8" Date: Mon, 10 Oct 2011 11:24:05 +0200 Message-ID: <1318238645.29415.426.camel@pasglop> Mime-Version: 1.0 Cc: netdev@vger.kernel.org, Yevgeny Petrilin , Eli Cohen , David Laight , Thadeu Lima de Souza Cascardo , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2011-10-10 at 11:16 +0200, Eli Cohen wrote: > Until then I think we need to have the logic working right on ppc and > measure if blue flame buys us any improvement in ppc. If that's not > the case (e.g because write combining is not working), then maybe we > should avoid using blueflame in ppc. > Could any of the guys from IBM check this and give us feedback? I don't have the necessary hardware myself to test that but maybe Thadeu can. Note that for WC to work, things must be mapped non-guarded. You can do that by using ioremap_prot() with pgprot_noncached_wc(PAGE_KERNEL) or ioremap_wc() (dunno how "generic" the later is). >>From there, you should get write combining provided that you don't have barriers between every access (ie those copy operations in their current form should do the trick). Cheers, Ben. > > Maybe it's time for us to revive those discussions about providing a > > good set of relaxed MMIO accessors with explicit barriers :-) > > > > Cheers, > > Ben. > >