From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?windows-1252?Q?Matias_Bj=F8rling?= Subject: Re: [PATCH 1/6] block: add support for carrying a stream ID in a bio Date: Tue, 24 Mar 2015 18:11:10 +0100 Message-ID: <55119AAE.9030202@bjorling.me> References: <1427210823-5283-1-git-send-email-axboe@fb.com> <1427210823-5283-2-git-send-email-axboe@fb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: ming.l@ssi.samsung.com To: Jens Axboe , axboe@kernel.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Return-path: Received: from mail-lb0-f170.google.com ([209.85.217.170]:33276 "EHLO mail-lb0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932502AbbCXRLP (ORCPT ); Tue, 24 Mar 2015 13:11:15 -0400 Received: by lbcmq2 with SMTP id mq2so35614116lbc.0 for ; Tue, 24 Mar 2015 10:11:13 -0700 (PDT) In-Reply-To: <1427210823-5283-2-git-send-email-axboe@fb.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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