From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH] fcoe: Reduce max_sectors to 1024 Date: Wed, 09 Jul 2014 08:40:30 +0200 Message-ID: <53BCE3DE.6000605@suse.de> References: <1404886581-3218-1-git-send-email-hare@suse.de> <20140709061838.GA28335@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor2.suse.de ([195.135.220.15]:37078 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271AbaGIGkd (ORCPT ); Wed, 9 Jul 2014 02:40:33 -0400 In-Reply-To: <20140709061838.GA28335@infradead.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Christoph Hellwig Cc: James Bottomley , linux-scsi@vger.kernel.org, Vasu Dev On 07/09/2014 08:18 AM, Christoph Hellwig wrote: > On Wed, Jul 09, 2014 at 08:16:21AM +0200, Hannes Reinecke wrote: >> The DDP offload on ixgbe is only capable of handling requests up >> to 1024 sectors. So we should be exposing this to avoid spurious >> messages about 'not enough user buffers'. > > Shouldn't the network driver be able to communicate it's offload > capabilities to the fcoe core? I'd be happy to take this as an iteri= m > fix if there's a comment explaining it, but long-term it should be > driver specific. > ixgbe can handle up to 256 sgl elements, but the maximum single I/O=20 size is 256 pages. This translates into 1024 sectors. And seeing that the 'fcoe' driver is effectively tied to ixgbe ATM I=20 doubt it's worth investing in yet another callout here. Intel, can you clarify on i40e? Is it FCoE capable? If so it might be worth adding a configuration knob here. Unless i40e has the same limitations as ixgbe ... Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: J. Hawn, J. Guild, F. Imend=F6rffer, HRB 16746 (AG N=FCrnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html