From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CE05C282C7 for ; Thu, 31 Jan 2019 10:04:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5136720B1F for ; Thu, 31 Jan 2019 10:04:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731950AbfAaKEE (ORCPT ); Thu, 31 Jan 2019 05:04:04 -0500 Received: from mx2.suse.de ([195.135.220.15]:47846 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726316AbfAaKEC (ORCPT ); Thu, 31 Jan 2019 05:04:02 -0500 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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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