From: Benjamin LaHaise Subject: Re: [PATCH] ext4: add noorlov parameter to avoid spreading of directory inodes Date: Wed, 2 Oct 2013 12:52:10 -0400 Message-ID: <20131002165210.GA16076@kvack.org> References: <20131001160817.GA2295@kvack.org> <20131002144759.GB32181@quack.suse.cz> <524C3574.7020106@redhat.com> <20131002153101.GE4353@kvack.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Eric Sandeen , Jan Kara , Theodore Ts'o , Andreas Dilger , linux-ext4@vger.kernel.org To: =?utf-8?B?THVrw6HFoQ==?= Czerner Return-path: Received: from kanga.kvack.org ([205.233.56.17]:58046 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753810Ab3JBQwK (ORCPT ); Wed, 2 Oct 2013 12:52:10 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Oct 02, 2013 at 06:44:56PM +0200, Luk=C3=A1=C5=A1 Czerner wrote= : > What is the frequency of unlink operation in comparison to file > creation ? There is a possible issue with the global goal cursors > s_mb_last_group and s_mb_last_start which might make your files > increasingly scattered across the disk. I've attempted to address > this problem with my patch unlink() is 1:1 with creation. The storage on disk is essentially used= =20 as an elastic buffer for the rest of the system. That said, unlink() m= ay=20 not occur for minutes, hours or days. In terms of actual allocation pattern on disk, using fallocate() is=20 sufficient to ensure that files on disk are usually limited to 1 extent= ,=20 and allocated immediately following each other. Without fallocate(), I= =20 was seeing allocations aligned to 2048 block boundaries for 9MB files,=20 which hurt performance quite a bit. > ext4: Try to better reuse recently freed space >=20 > What is the usual size of the files this application is creating ? It varies. The target is 8MB, but it ranges from 5MB to 22MB. In the=20 worst case it can be as small as 4KB. -ben > Thanks! > -Lukas --=20 "Thought is the essence of where you are now." -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html