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_HELO_NONE,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 92F7BC04AAF for ; Tue, 21 May 2019 08:25:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 701DE216B7 for ; Tue, 21 May 2019 08:25:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726947AbfEUIZb (ORCPT ); Tue, 21 May 2019 04:25:31 -0400 Received: from mx2.suse.de ([195.135.220.15]:50394 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726767AbfEUIZb (ORCPT ); Tue, 21 May 2019 04:25:31 -0400 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 AA0DAAD94; Tue, 21 May 2019 08:25:29 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id EF1FD1E3C72; Tue, 21 May 2019 10:25:28 +0200 (CEST) Date: Tue, 21 May 2019 10:25:28 +0200 From: Jan Kara To: 'Christoph Hellwig' Cc: kanchan , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, prakash.v@samsung.com, anshul@samsung.com, "Martin K. Petersen" Subject: Re: [PATCH v5 0/7] Extend write-hint framework, and add write-hint for Ext4 journal Message-ID: <20190521082528.GA17709@quack2.suse.cz> References: <1556191202-3245-1-git-send-email-joshi.k@samsung.com> <20190510170249.GA26907@infradead.org> <00fb01d50c71$dd358e50$97a0aaf0$@samsung.com> <20190520142719.GA15705@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190520142719.GA15705@infradead.org> 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 Mon 20-05-19 07:27:19, 'Christoph Hellwig' wrote: > On Fri, May 17, 2019 at 11:01:55AM +0530, kanchan wrote: > > Sorry but can you please elaborate the issue? I do not get what is being > > statically allocated which was globally available earlier. > > If you are referring to nvme driver, available streams at subsystem level > > are being reflected for all namespaces. This is same as earlier. > > There is no attempt to explicitly allocate (using dir-receive) or reserve > > streams for any namespace. > > Streams will continue to get allocated/released implicitly as and when > > writes (with stream id) arrive. > > We have made a concious decision that we do not want to expose streams > as an awkward not fish not flesh interface, but instead life time hints. > > I see no reason to change from and burden the whole streams complexity > on other in-kernel callers. I'm not following the "streams complexity" you talk about. At least the usecase Kanchan speaks about here is pretty simple for the filesystem - tagging journal writes with special stream id. I agree that something like dynamically allocating available stream ids to different purposes is complex and has uncertain value but this "static stream id for particular purpose" looks simple and sensible to me and Kanchan has shown significant performance benefits for some drives. After all you can just think about it like RWH_WRITE_LIFE_JOURNAL type of hint available for the kernel... Honza -- Jan Kara SUSE Labs, CR