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From: Jan Kara <jack@suse.cz>
To: "Weiny, Ira" <ira.weiny@intel.com>
Cc: 'Jason Gunthorpe' <jgg@ziepe.ca>,
	Davidlohr Bueso <dave@stgolabs.net>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"dledford@redhat.com" <dledford@redhat.com>,
	"jack@suse.de" <jack@suse.de>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Dalessandro, Dennis" <dennis.dalessandro@intel.com>,
	"Marciniszyn, Mike" <mike.marciniszyn@intel.com>,
	Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH 3/6] drivers/IB,qib: do not use mmap_sem
Date: Thu, 31 Jan 2019 11:04:00 +0100	[thread overview]
Message-ID: <20190131100400.GC19222@quack2.suse.cz> (raw)
In-Reply-To: <2807E5FD2F6FDA4886F6618EAC48510E79BA6A27@CRSMSX101.amr.corp.intel.com>

On Wed 30-01-19 18:01:33, Weiny, Ira wrote:
> > 
> > On Tue, Jan 29, 2019 at 10:50:05AM -0800, Ira Weiny wrote:
> > > > .. and I'm looking at some of the other conversions here.. *most
> > > > likely* any caller that is manipulating rlimit for get_user_pages
> > > > should really be calling get_user_pages_longterm, so they should not
> > > > be converted to use _fast?
> > >
> > > Is this a question?  I'm not sure I understand the meaning here?
> > 
> > More an invitation to disprove the statement
> 
> Generally I agree.  But would be best if we could get fast GUP for
> performance.  I have not worked out if that will be possible with the
> final "longterm" solutions.

Initially probably not, longer-term it might be added if there are
performance data supporting that (i.e., showing real workload that would
benefit). In principle there's nothing that would prevent gup_fast like
functionality for long-term pins but I expect there will be always
additional overhead (compared to plain gup_fast()) of establishing
something like leases to identify long-term pins. But we haven't figured
out the details yet. For now we concentrate on fixing short-term pins and
issues with those.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR


  reply	other threads:[~2019-01-31 10:04 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-21 17:42 [PATCH v2 -next 0/6] mm: make pinned_vm atomic and simplify users Davidlohr Bueso
2019-01-21 17:42 ` [PATCH 1/6] mm: make mm->pinned_vm an atomic64 counter Davidlohr Bueso
2019-01-21 21:51   ` Christopher Lameter
2019-01-21 21:51     ` Christopher Lameter
2019-01-22  9:56   ` Jan Kara
2019-01-22 15:45   ` Daniel Jordan
2019-01-23 18:33   ` Jason Gunthorpe
2019-01-28 21:10     ` Andrew Morton
2019-01-21 17:42 ` [PATCH 2/6] mic/scif: do not use mmap_sem Davidlohr Bueso
2019-01-21 17:42 ` [PATCH 3/6] drivers/IB,qib: " Davidlohr Bueso
2019-01-28 23:31   ` Jason Gunthorpe
2019-01-29  4:46     ` Jason Gunthorpe
2019-01-29 14:14       ` Davidlohr Bueso
2019-01-29 18:50       ` Ira Weiny
2019-01-29 23:19         ` Jason Gunthorpe
2019-01-30 18:01           ` Weiny, Ira
2019-01-31 10:04             ` Jan Kara [this message]
2019-01-21 17:42 ` [PATCH 4/6] drivers/IB,hfi1: do not se mmap_sem Davidlohr Bueso
2019-01-21 17:42 ` [PATCH 5/6] drivers/IB,usnic: reduce scope of mmap_sem Davidlohr Bueso
2019-01-21 17:42 ` [PATCH 6/6] drivers/IB,core: " Davidlohr Bueso
2019-01-21 18:32   ` Jason Gunthorpe
2019-01-21 19:12     ` Davidlohr Bueso
2019-01-21 21:53   ` Christopher Lameter
2019-01-21 21:53     ` Christopher Lameter
  -- strict thread matches above, loose matches on Subject: below --
2019-01-15 18:12 [PATCH -next 0/6] mm: make pinned_vm atomic and simplify users Davidlohr Bueso
2019-01-15 18:12 ` [PATCH 3/6] drivers/IB,qib: do not use mmap_sem Davidlohr Bueso
2019-01-15 20:29   ` Ira Weiny

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