From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756725Ab3AHQsa (ORCPT ); Tue, 8 Jan 2013 11:48:30 -0500 Received: from mail-pb0-f44.google.com ([209.85.160.44]:34246 "EHLO mail-pb0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756480Ab3AHQs2 (ORCPT ); Tue, 8 Jan 2013 11:48:28 -0500 Date: Tue, 8 Jan 2013 08:48:24 -0800 From: Kent Overstreet To: Jeff Moyer Cc: Jens Axboe , linux-kernel@vger.kernel.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, zab@redhat.com, bcrl@kvack.org, viro@zeniv.linux.org.uk, tytso@mit.edu Subject: Re: [PATCH 29/32] block, aio: Batch completion for bios/kiocbs Message-ID: <20130108164824.GB25098@localhost> References: <1356573611-18590-1-git-send-email-koverstreet@google.com> <1356573611-18590-32-git-send-email-koverstreet@google.com> <50E69F5B.8060902@kernel.dk> <20130107233443.GG26407@google.com> <20130108160654.GA25098@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 08, 2013 at 11:15:37AM -0500, Jeff Moyer wrote: > Kent Overstreet writes: > > > On Tue, Jan 08, 2013 at 10:33:18AM -0500, Jeff Moyer wrote: > >> Kent Overstreet writes: > >> > >> >> Is the rbtree really faster than a basic (l)list and a sort before > >> >> completing them? Would be simpler. > >> > > >> > Well, depends. With one or two kioctxs? The list would definitely be > >> > faster, but I'm loathe to use an O(n^2) algorithm anywhere where the > >> > input size isn't strictly controlled, and I know of applications out > >> > there that use tons of kioctxs. > >> > >> Out of curiosity, what applications do you know of that use tons of > >> kioctx's? > > > > "tons" is relative I suppose, but before this patch series sharing a > > kioctx between threads was really bad for performance and... you know > > how people can be with threads. > > I wasn't questioning the merits of the patch, I was simply curious to > know how aio is being (ab)used in the wild. So, is this some internal > tool, then, or what? Oh, didn't think you were, I just never looked for actual numbers. Yeah, some internal library code is what I was referring to, but from the story of how it evolved I don't think it's unusual.