From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933122AbbCXRLx (ORCPT ); Tue, 24 Mar 2015 13:11:53 -0400 Received: from mail-lb0-f171.google.com ([209.85.217.171]:36074 "EHLO mail-lb0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932402AbbCXRLP (ORCPT ); Tue, 24 Mar 2015 13:11:15 -0400 Message-ID: <55119AAE.9030202@bjorling.me> Date: Tue, 24 Mar 2015 18:11:10 +0100 From: =?windows-1252?Q?Matias_Bj=F8rling?= Organization: Paletta User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Jens Axboe , axboe@kernel.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org CC: ming.l@ssi.samsung.com Subject: Re: [PATCH 1/6] block: add support for carrying a stream ID in a bio References: <1427210823-5283-1-git-send-email-axboe@fb.com> <1427210823-5283-2-git-send-email-axboe@fb.com> In-Reply-To: <1427210823-5283-2-git-send-email-axboe@fb.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/24/2015 04:26 PM, Jens Axboe wrote: > The top bits of bio->bi_flags are reserved for keeping the > allocation pool, set aside the next four bits for carrying > a stream ID. That leaves us with support for 15 streams, > 0 is reserved as a "stream not set" value. 15 streams seem very limited. Can this be extended? e.g. 16 bits. 15 streams is enough for 1-4 applications. More, and applications starts to fight over the same stream id's, leading them to place different age data in same flash blocks and push us back to square one. I understand that Samsung multi-stream SSD supports a limited amount of streams, more advance implementations should provide higher limits. Thanks, Matias