From: Joachim Fenkes <FENKES@de.ibm.com>
To: Arnd Bergmann <arnd@arndb.de>,
"OF-EWG" <ewg@lists.openfabrics.org>,
"OF-General" <general@lists.openfabrics.org>,
LKML <linux-kernel@vger.kernel.org>,
linuxppc-dev@ozlabs.org, Roland Dreier <rdreier@cisco.com>,
Roland Dreier <rolandd@cisco.com>
Cc: Christoph Raisch <raisch@de.ibm.com>,
Marcus Eder <meder@de.ibm.com>,
Stefan Roscher <stefan.roscher@de.ibm.com>
Subject: Re: [PATCH] IB/ehca: Serialize HCA-related hCalls on POWER5
Date: Mon, 10 Dec 2007 18:59:16 +0100 [thread overview]
Message-ID: <OF9AA24809.F691A5CC-ONC12573AD.006155D6-C12573AD.0062ABE2@de.ibm.com> (raw)
In-Reply-To: <OF85E31FAA.DADA6039-ONC12573AA.005439C8-C12573AA.005A132E@LocalDomain>
Hi, guys,
> We're taking this to the firmware architects at the moment, but they're
not
> very fond of the idea of reporting the absence of bugs through
capability
> flags, as this could quickly lead to the exhaustion of flag bits. We'll
let
> the discussion stew for a bit, but if we don't get this flag, we'll have
to
> resort to the CPU features.
The architects have spoken, and we're getting a capability flag for this.
I'll repost my patch with new autodetection code that doesn't involve
checking the processor version.
> > > Regarding the performance problem, have you checked whether
converting all
> > > your spin_lock_irqsave to spin_lock/spin_lock_irq improves your
performance
> > > on the older machines? Maybe it's already fast enough that way.
> >
> > It does seem that the only places that the hcall_lock is taken also
> > use msleep, so they must always be in process context. So you can
> > safely just use spin_lock(), right?
>
> As Arnd said, there are hCalls that will never return H_LONG_BUSY_*,
such as
> H_QUERY_PORT and chums, so they will never sleep. The surrounding
functions,
> though, are not prepared to be called from interrupt context (GFP_KERNEL
comes
> to mind), so I agree that a simple spin_lock() will suffice. Thanks,
Arnd, for
> pointing this out.
As I pointed out in my earlier mail, there's still an issue with
map_phys_fmr possibly sleeping. Let's keep the irqsave for the time being
and revisit this part once we find a solution to map_phys_fmr.
Regards,
Joachim
next parent reply other threads:[~2007-12-10 17:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <OF85E31FAA.DADA6039-ONC12573AA.005439C8-C12573AA.005A132E@LocalDomain>
2007-12-10 17:59 ` Joachim Fenkes [this message]
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
2007-12-07 16:25 ` Joachim Fenkes
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