Re: [PATCH v12 0/10] Support Write-Through mapping on x86

From: "Luis R. Rodriguez" <mcgrof@suse.com>
To: Andy Lutomirski <luto@amacapital.net>,
	linux-rdma@vger.kernel.org, "Marciniszyn,
	Mike" <mike.marciniszyn@intel.com>,
	Doug Ledford <dledford@redhat.com>,
	roland@purestorage.com
Cc: Toshi Kani <toshi.kani@hp.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arnd Bergmann <arnd@arndb.de>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	X86 ML <x86@kernel.org>, linux-nvdimm <linux-nvdimm@ml01.01.org>,
	Juergen Gross <jgross@suse.com>,
	Stefan Bader <stefan.bader@canonical.com>,
	Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
	Yigal Korman <yigal@plexistor.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	"Elliott, Robert (Server Storage)" <Elliott@hp.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v12 0/10] Support Write-Through mapping on x86
Date: Tue, 2 Jun 2015 22:01:53 +0200	[thread overview]
Message-ID: <20150602200153.GN23057@wotan.suse.de> (raw)
In-Reply-To: <CALCETrXho_xx27yq_Ji+xpD785xWGNpL-Tgbn17S8RbK6unQWA@mail.gmail.com>

On Tue, Jun 02, 2015 at 12:50:09PM -0700, Andy Lutomirski wrote:
> On Tue, Jun 2, 2015 at 12:43 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
> > On Tue, Jun 02, 2015 at 12:46:48PM -0600, Toshi Kani wrote:
> >> On Tue, 2015-06-02 at 18:21 +0200, Luis R. Rodriguez wrote:
> >> > On Mon, Jun 01, 2015 at 01:36:23PM -0600, Toshi Kani wrote:
> >> > > This patchset adds support of Write-Through (WT) mapping on x86.
> >> > > The study below shows that using WT mapping may be useful for
> >> > > non-volatile memory.
> >> > >
> >> > > http://www.hpl.hp.com/techreports/2012/HPL-2012-236.pdf
> >> > >
> >> > > The patchset consists of the following changes.
> >> > >  - Patch 1/10 to 6/10 add ioremap_wt()
> >> > >  - Patch 7/10 adds pgprot_writethrough()
> >> > >  - Patch 8/10 to 9/10 add set_memory_wt()
> >> > >  - Patch 10/10 changes the pmem driver to call ioremap_wt()
> >> > >
> >> > > All new/modified interfaces have been tested.
> >> > >
> >> > > The patchset is based on:
> >> > > git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git#tip-mm-2
> >> >
> >> > While at it can you also look at:
> >> >
> >> > mcgrof@ergon ~/linux-next (git::master)$ git grep -4 "writethrough" drivers/infiniband/
> >>
> >> Thanks for checking this.  The inifiniband driver uses WT mappings on
> >> powerpc without proper WT interfaces defined.
> >
> > Right.
> >
> >>  They can be cleaned up by
> >> a separate patch series to support WT on powerpc in the same way after
> >> this patchset (support WT on x86) is settled.
> >
> > Who's gonna do that work though? How much work is it ? Is it too much to ask
> > to roll it in this series?
> >
> 
> I think the driver maintainers should do it.  For all I know,
> something will go horribly wrong if those drivers suddenly start using
> WT on x86.

OK. Letting qib driver folks know.

 Luis