From: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
paulus@samba.org, mpe@ellerman.id.au,
linuxppc-dev@lists.ozlabs.org,
Mike Marciniszyn <infinipath@intel.com>,
Doug Ledford <dledford@redhat.com>,
Sean Hefty <sean.hefty@intel.com>,
Hal Rosenstock <hal.rosenstock@gmail.com>,
linux-rdma@vger.kernel.org
Subject: Re: [PATCH V2] powerpc/infiniband: Use cache inhibitted and guarded mapping on powerpc
Date: Fri, 22 Apr 2016 10:09:27 -0600 [thread overview]
Message-ID: <20160422160927.GB12897@obsidianresearch.com> (raw)
In-Reply-To: <1461278876.3135.18.camel@kernel.crashing.org>
On Fri, Apr 22, 2016 at 08:47:56AM +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2016-04-20 at 03:58 -0400, Aneesh Kumar K.V wrote:
> > The driver was requesting for a writethrough mapping. But with thoses
> > flags we will end up with a SAO mapping because we now have memory
> > conherence always enabled. ie, the existing mapping will end up with
> > a WIMG value 0b1110 which is Strong Access Order.
> >
> > Update this to use cache inhibitted guarded mapping
>
> Why guarded ? If it's performance sensitive (and the driver has
> appropriate barriers where needed), you will get write combining
> without guarded, you won't with it.
This driver uses uncached write combining on x86
Jason
next prev parent reply other threads:[~2016-04-22 16:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-20 7:58 [PATCH V2] powerpc/infiniband: Use cache inhibitted and guarded mapping on powerpc Aneesh Kumar K.V
2016-04-20 16:29 ` Marciniszyn, Mike
2016-04-26 11:03 ` Michael Ellerman
2016-04-21 22:47 ` Benjamin Herrenschmidt
2016-04-22 16:09 ` Jason Gunthorpe [this message]
2016-04-23 8:25 ` Benjamin Herrenschmidt
2016-04-24 17:33 ` Aneesh Kumar K.V
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