From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Weiny, Ira" <ira.weiny@intel.com>
Cc: "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Davidlohr Bueso <dave@stgolabs.net>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"Marciniszyn, Mike" <mike.marciniszyn@intel.com>,
"Dalessandro, Dennis" <dennis.dalessandro@intel.com>,
Doug Ledford <dledford@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Williams, Dan J" <dan.j.williams@intel.com>
Subject: Re: [PATCH 0/3] Add gup fast + longterm and use it in HFI1
Date: Mon, 11 Feb 2019 15:23:35 -0700 [thread overview]
Message-ID: <20190211222335.GK24692@ziepe.ca> (raw)
In-Reply-To: <2807E5FD2F6FDA4886F6618EAC48510E79BCF04C@CRSMSX101.amr.corp.intel.com>
On Mon, Feb 11, 2019 at 09:14:56PM +0000, Weiny, Ira wrote:
> >
> > On Mon, Feb 11, 2019 at 12:16:40PM -0800, ira.weiny@intel.com wrote:
> > > From: Ira Weiny <ira.weiny@intel.com>
> > >
> > > NOTE: This series depends on my clean up patch to remove the write
> > > parameter from gup_fast_permitted()[1]
> > >
> > > HFI1 uses get_user_pages_fast() due to it performance advantages.
> > > Like RDMA,
> > > HFI1 pages can be held for a significant time. But
> > > get_user_pages_fast() does not protect against mapping of FS DAX pages.
> >
> > If HFI1 can use the _fast varient, can't all the general RDMA stuff use it too?
> >
> > What is the guidance on when fast vs not fast should be use?
>
> Right now it can't because it holds mmap_sem across the call. Once
> Shiraz's patches are accepted removing the umem->hugetlb flag I
> think we can change umem.c.
Okay, that make sense, we should change it when Shiraz's patches are
merged
> Also, it specifies FOLL_FORCE which can't currently be specified
> with gup fast. One idea I had was to change get_user_pages_fast()
> to use gup_flags instead of a single write flag. But that proved to
> be a very big cosmetic change across a lot of callers so I went this
> way.
I think you should do it.. :)
Jason
next prev parent reply other threads:[~2019-02-11 22:23 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-11 20:16 [PATCH 0/3] Add gup fast + longterm and use it in HFI1 ira.weiny
2019-02-11 20:16 ` [PATCH 1/3] mm/gup: Change "write" parameter to flags ira.weiny
2019-02-11 20:16 ` [PATCH 2/3] mm/gup: Introduce get_user_pages_fast_longterm() ira.weiny
2019-02-11 20:39 ` Jason Gunthorpe
2019-02-11 21:13 ` John Hubbard
2019-02-11 21:26 ` Ira Weiny
2019-02-11 21:39 ` John Hubbard
2019-02-11 21:45 ` Dan Williams
2019-02-11 21:52 ` Ira Weiny
2019-02-11 22:01 ` John Hubbard
2019-02-11 22:06 ` Jason Gunthorpe
2019-02-11 22:55 ` Dan Williams
2019-02-11 23:04 ` Weiny, Ira
2019-02-11 23:25 ` Jason Gunthorpe
2019-02-12 0:08 ` Ira Weiny
2019-02-11 20:16 ` [PATCH 3/3] IB/HFI1: Use new get_user_pages_fast_longterm() ira.weiny
2019-02-11 20:34 ` [PATCH 0/3] Add gup fast + longterm and use it in HFI1 Davidlohr Bueso
2019-02-11 20:47 ` Jason Gunthorpe
2019-02-11 21:42 ` Ira Weiny
2019-02-11 22:22 ` Jason Gunthorpe
2019-02-11 22:40 ` Weiny, Ira
2019-02-11 22:50 ` Jason Gunthorpe
2019-02-11 21:29 ` Ira Weiny
2019-02-11 20:40 ` Jason Gunthorpe
2019-02-11 21:14 ` Weiny, Ira
2019-02-11 22:23 ` Jason Gunthorpe [this message]
2019-02-13 23:04 ` [PATCH V2 0/7] Add FOLL_LONGTERM to GUP fast and use it ira.weiny
2019-02-13 23:04 ` [PATCH V2 1/7] mm/gup: Replace get_user_pages_longterm() with FOLL_LONGTERM ira.weiny
2019-02-13 23:04 ` [PATCH V2 2/7] mm/gup: Change write parameter to flags in fast walk ira.weiny
2019-02-13 23:04 ` [PATCH V2 3/7] mm/gup: Change GUP fast to use flags rather than a write 'bool' ira.weiny
2019-02-13 23:04 ` [PATCH V2 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast ira.weiny
2019-02-13 23:04 ` [PATCH V2 5/7] IB/hfi1: Use the new FOLL_LONGTERM flag to get_user_pages_fast() ira.weiny
2019-02-13 23:04 ` [PATCH V2 6/7] IB/qib: " ira.weiny
2019-02-13 23:04 ` [PATCH V2 7/7] IB/mthca: " ira.weiny
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