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[195.135.220.15]) by mx.google.com with ESMTPS id e10-v6si1996111eji.18.2019.01.31.02.04.01 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 31 Jan 2019 02:04:01 -0800 (PST) Received-SPF: pass (google.com: domain of jack@suse.cz designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jack@suse.cz designates 195.135.220.15 as permitted sender) smtp.mailfrom=jack@suse.cz X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C4BCBADA2; Thu, 31 Jan 2019 10:04:00 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 5E9CB1E3FFD; Thu, 31 Jan 2019 11:04:00 +0100 (CET) Date: Thu, 31 Jan 2019 11:04:00 +0100 From: Jan Kara To: "Weiny, Ira" Cc: 'Jason Gunthorpe' , Davidlohr Bueso , "akpm@linux-foundation.org" , "dledford@redhat.com" , "jack@suse.de" , "linux-rdma@vger.kernel.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "Dalessandro, Dennis" , "Marciniszyn, Mike" , Davidlohr Bueso Subject: Re: [PATCH 3/6] drivers/IB,qib: do not use mmap_sem Message-ID: <20190131100400.GC19222@quack2.suse.cz> References: <20190121174220.10583-1-dave@stgolabs.net> <20190121174220.10583-4-dave@stgolabs.net> <20190128233140.GA12530@ziepe.ca> <20190129044607.GL25106@ziepe.ca> <20190129185005.GC10129@iweiny-DESK2.sc.intel.com> <20190129231903.GA5352@ziepe.ca> <2807E5FD2F6FDA4886F6618EAC48510E79BA6A27@CRSMSX101.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2807E5FD2F6FDA4886F6618EAC48510E79BA6A27@CRSMSX101.amr.corp.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 SUSE Labs, CR