From: Joachim Fenkes <FENKES@de.ibm.com>
To: "Caitlin Bestler" <caitlin.bestler@neterion.com>
Cc: "Arnd Bergmann" <arnd@arndb.de>,
caitlin.bestler@gmail.com,
OF-General <general@lists.openfabrics.org>,
LKML <linux-kernel@vger.kernel.org>,
linuxppc-dev@ozlabs.org, "Or Gerlitz" <ogerlitz@voltaire.com>,
"Roland Dreier" <rdreier@cisco.com>,
Stefan Roscher <stefan.roscher@de.ibm.com>
Subject: Re: [ofa-general] Re: [ewg] Re: [PATCH] IB/ehca: Serialize HCA-related hCalls on POWER5
Date: Thu, 13 Dec 2007 21:59:50 +0100 [thread overview]
Message-ID: <OFD5B7D5E6.3538DC2A-ONC12573B0.0072D42A-C12573B0.00735730@de.ibm.com> (raw)
In-Reply-To: <469958e00712131122s661dd970ud359389e1c6637d4@mail.gmail.com>
caitlin.bestler@gmail.com wrote on 13.12.2007 20:22:49:
> On Dec 13, 2007 12:30 AM, Or Gerlitz <ogerlitz@voltaire.com> wrote:
> > The current implementation of the open iscsi initiator makes sure to
> > issue commands in thread (sleepable) context, see iscsi_xmitworker and
> > references to it in drivers/scsi/libiscsi.c , so this keeps ehca users
> > safe for the time being.
> I agree, *some* form of FMR support is important for iSER (and probably
> for NFS over RDMA as well). Rather than adding a crippled NO FMR
> mode it would make more sense to add support for FMR Work Requests.
> I'm not certain what, if any, impact that would have on the Power5
problem,
> but that's certainly a cleaner path for iWARP.
Well, FMR WRs wouldn't change the eHCA issue -- the driver would have to
make an hCall in any case, and the architecture says that the hCalls used
in this scenario might return H_LONG_BUSY, causing the driver to sleep. No
way around that. Because of this, eHCA's FMRs are actually standard MRs
with a different API.
If, as Or said, the iSCSI initiator issues commands in sleepable context
anyway, nothing would be lost by using standard MRs as a fallback solution
if FMRs aren't available, would it?
J.
next prev parent reply other threads:[~2007-12-13 21:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-06 15:07 [PATCH] IB/ehca: Serialize HCA-related hCalls on POWER5 Joachim Fenkes
2007-12-06 15:48 ` Arnd Bergmann
2007-12-06 18:27 ` Roland Dreier
2007-12-07 9:58 ` Arnd Bergmann
2007-12-09 23:22 ` Roland Dreier
2007-12-10 17:41 ` Joachim Fenkes
2007-12-10 21:47 ` Roland Dreier
2007-12-11 8:38 ` Joachim Fenkes
2007-12-12 12:14 ` [ewg] " Or Gerlitz
2007-12-12 16:02 ` Christoph Raisch
2007-12-12 19:09 ` Roland Dreier
2007-12-13 8:30 ` Or Gerlitz
2007-12-13 19:22 ` [ofa-general] " Caitlin Bestler
2007-12-13 20:59 ` Joachim Fenkes [this message]
2007-12-13 21:08 ` Caitlin Bestler
2007-12-13 21:35 ` Joachim Fenkes
2007-12-13 21:48 ` [ofa-general] Re: [ewg] Re: [PATCH] IB/ehca: SerializeHCA-related " Sean Hefty
2007-12-07 16:25 ` [PATCH] IB/ehca: Serialize HCA-related " Joachim Fenkes
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