Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932216AbcLHD5f (ORCPT ); Wed, 7 Dec 2016 22:57:35 -0500 Received: from mail-pf0-f175.google.com ([209.85.192.175]:35555 "EHLO mail-pf0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752704AbcLHD5d (ORCPT ); Wed, 7 Dec 2016 22:57:33 -0500 Subject: Re: [RFC 06/10] block: use tida as small id allocator To: Rasmus Villemoes , Tejun Heo , Andrew Morton References: <1481160187-9652-1-git-send-email-linux@rasmusvillemoes.dk> <1481160187-9652-7-git-send-email-linux@rasmusvillemoes.dk> Cc: linux-kernel@vger.kernel.org, Lai Jiangshan , Greg Kroah-Hartman , linux-block@vger.kernel.org From: Jens Axboe Message-ID: Date: Wed, 7 Dec 2016 20:56:27 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <1481160187-9652-7-git-send-email-linux@rasmusvillemoes.dk> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 661 Lines: 17 On 12/07/2016 06:23 PM, Rasmus Villemoes wrote: > A struct ida ends up costing > 16 KB of runtime memory, which is quite > a lot for something which on my laptop as of this writing has handed > out 27 ids in its lifetime. So use the simpler and lighter-weight > struct tida. I'm worried that your example of your laptop isn't an all encompassing test case. How well does the simplified ida allocator work for tens of thousands of disks, at scan time? SCSI is notorious for setting up and tearing down a ton of queues at probe time. Unless we have more testing than 'it works on my laptop and saves 16k', I'm not super intereted in the patch. -- Jens Axboe