From: Zeev Tarantov Subject: problem(?) in ext4 or mke2fs Date: Sun, 3 Apr 2011 21:07:43 +0300 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 To: linux-ext4@vger.kernel.org Return-path: Received: from mail-pz0-f46.google.com ([209.85.210.46]:35057 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752715Ab1DCSIE (ORCPT ); Sun, 3 Apr 2011 14:08:04 -0400 Received: by pzk9 with SMTP id 9so1102893pzk.19 for ; Sun, 03 Apr 2011 11:08:03 -0700 (PDT) Sender: linux-ext4-owner@vger.kernel.org List-ID: While testing zram I ran a script that creates a block devices, creates a filesystem on in and untars Qt on that filesystem. I was surprised to find ext4_mb_scan_aligned near the top of the profile output. This was evidently because the command "mke2fs -t ext4 -m 0 -I 128 -O ^has_journal,^ext_attr " created a filesystem with (output of tune2fs): RAID stride: 1 RAID stripe width: 1 I thought this strange and removed these values using debugfs: set_super_value raid_stride 0 set_super_value raid_stripe_width 0 With this "fix" the symbol ext4_mb_scan_aligned disappeared from perf's output: 18.98% -3.66% gzip [.] zip 0.00% +14.84% [kernel.kallsyms] [k] ext4_mb_scan_aligned 17.91% -3.44% gzip [.] treat_file.part.4.2264 13.73% -2.47% [csnappy_compress] [k] snappy_compress_fragment 3.96% -0.77% [kernel.kallsyms] [k] copy_user_generic_string 3.05% -0.41% libc-2.13.so [.] __memcpy_ssse3 0.89% +1.49% [kernel.kallsyms] [k] _raw_spin_lock 2.63% -0.49% [kernel.kallsyms] [k] __memcpy 1.61% -0.17% [kernel.kallsyms] [k] __memset 0.78% -0.11% [kernel.kallsyms] [k] ext4_mark_iloc_dirty 0.63% -0.11% [kernel.kallsyms] [k] system_call 0.66% -0.14% gzip [.] treat_stdin.2262 0.58% -0.12% libc-2.13.so [.] _int_malloc This is using mke2fs 1.41.14 (22-Dec-2010) on Linux 2.6.38.2. Is this expected behavior? Do you need me to provide more information? regards, -Z.T.