Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753484Ab1EPRSi (ORCPT ); Mon, 16 May 2011 13:18:38 -0400 Received: from smtp-out.google.com ([74.125.121.67]:8842 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751668Ab1EPRSh convert rfc822-to-8bit (ORCPT ); Mon, 16 May 2011 13:18:37 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=BU750R7AxiL0C7eaKYyxf7tiQciFrB9y/zC8Sh5kPUjSPkuVGyMiIWs/wCp8Wb/FPj wivRYhYtE0SRXSjIS/uA== MIME-Version: 1.0 In-Reply-To: References: <1305321545-17214-1-git-send-email-haldar@google.com> Date: Mon, 16 May 2011 10:18:33 -0700 Message-ID: Subject: Re: [PATCH] ext4: do not normalize block requests from fallocate. From: Vivek Haldar To: Lukas Czerner Cc: "Theodore Ts'o" , Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3467 Lines: 91 EXT4_GET_BLOCKS_* and EXT4_MB_HINT_* are different flag spaces and should not be mixed. ext4_ext_map_blocks should not be using EXT4_MB_HINT_*, it only uses EXT4_GET_BLOCKS_*. On Mon, May 16, 2011 at 2:39 AM, Lukas Czerner wrote: > On Fri, 13 May 2011, Vivek Haldar wrote: > >> Currently, an fallocate request of size slightly larger than a power of >> 2 is turned into two block requests, each a power of 2, with the extra >> blocks pre-allocated for future use. When an application calls >> fallocate, it already has an idea about how large the file may grow so >> there is usually little benefit to reserve extra blocks on the >> preallocation list. This reduces disk fragmentation. >> >> Tested: fsstress. Also verified manually that fallocat'ed files are >> contiguously laid out with this change (whereas without it they begin at >> power-of-2 boundaries, leaving blocks in between). CPU usage of >> fallocate is not appreciably higher. In a tight fallocate loop, CPU >> usage hovers between 5%-8% with this change, and 5%-7% without it. > > Hi Vivek, > > the patch looks good, but I do not understand why you are introducing > new #define when you can simply use EXT4_MB_HINT_NOPREALLOC and then in > the ext4_ext_map_blocks() just do : > > ar.flags |= (flags & EXT4_MB_HINT_NOPREALLOC) > > and you do not need to introduce new condition. Am I missing something ? > > Thanks! > -Lukas > >> >> Signed-off-by: Vivek Haldar >> --- >> ?fs/ext4/ext4.h ? ?| ? ?2 ++ >> ?fs/ext4/extents.c | ? ?5 ++++- >> ?2 files changed, 6 insertions(+), 1 deletions(-) >> >> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h >> index 076c5d2..e606d34 100644 >> --- a/fs/ext4/ext4.h >> +++ b/fs/ext4/ext4.h >> @@ -512,6 +512,8 @@ struct ext4_new_group_data { >> ? ? ? /* Convert extent to initialized after IO complete */ >> ?#define EXT4_GET_BLOCKS_IO_CONVERT_EXT ? ? ? ? ? ? ? (EXT4_GET_BLOCKS_CONVERT|\ >> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?EXT4_GET_BLOCKS_CREATE_UNINIT_EXT) >> + ? ? /* Don't normalize when fallocat'ing */ >> +#define EXT4_GET_BLOCKS_NO_NORMALIZE ? ? ? ? 0x0020 >> >> ?/* >> ? * Flags used by ext4_free_blocks >> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c >> index e363f21..f02dd52 100644 >> --- a/fs/ext4/extents.c >> +++ b/fs/ext4/extents.c >> @@ -3304,6 +3304,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, >> ? ? ? else >> ? ? ? ? ? ? ? /* disable in-core preallocation for non-regular files */ >> ? ? ? ? ? ? ? ar.flags = 0; >> + ? ? if (flags & EXT4_GET_BLOCKS_NO_NORMALIZE) >> + ? ? ? ? ? ? ar.flags |= EXT4_MB_HINT_NOPREALLOC; >> ? ? ? newblock = ext4_mb_new_blocks(handle, &ar, &err); >> ? ? ? if (!newblock) >> ? ? ? ? ? ? ? goto out2; >> @@ -3549,7 +3551,8 @@ retry: >> ? ? ? ? ? ? ? ? ? ? ? break; >> ? ? ? ? ? ? ? } >> ? ? ? ? ? ? ? ret = ext4_map_blocks(handle, inode, &map, >> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? EXT4_GET_BLOCKS_CREATE_UNINIT_EXT); >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? EXT4_GET_BLOCKS_CREATE_UNINIT_EXT | >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? EXT4_GET_BLOCKS_NO_NORMALIZE); >> ? ? ? ? ? ? ? if (ret <= 0) { >> ?#ifdef EXT4FS_DEBUG >> ? ? ? ? ? ? ? ? ? ? ? WARN_ON(ret <= 0); >> > > -- > -- Regards, Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/