Date:	Sat, 06 Apr 2013 09:29:48 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	Theodore Ts'o <tytso@....edu>, Mel Gorman <mgorman@...e.de>,
	linux-ext4@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Linux-MM <linux-mm@...ck.org>
Subject: Re: Excessive stall times on ext4 in 3.9-rc2

On 04/06/2013 01:16 AM, Theodore Ts'o wrote:
> On Sat, Apr 06, 2013 at 12:18:11AM +0200, Jiri Slaby wrote:
>> Ok, so now I'm runnning 3.9.0-rc5-next-20130404, it's not that bad, but
>> it still sucks. Updating a kernel in a VM still results in "Your system
>> is too SLOW to play this!" by mplayer and frame dropping.
> 
> What was the first kernel where you didn't have the problem?  Were you
> using the 3.8 kernel earlier, and did you see the interactivity
> problems there?

I'm not sure, as I am using -next like for ever. But sure, there was a
kernel which didn't ahve this problem.

> What else was running in on your desktop at the same time?

Nothing, just VM (kernel update from console) and mplayer2 on the host.
This is more-or-less reproducible with these two.

> How was
> the file system mounted,

Both are actually a single device /dev/sda5:
/dev/sda5 on /win type ext4 (rw,noatime,data=ordered)

Should I try writeback?

> and can you send me the output of dumpe2fs -h
> /dev/XXX?

dumpe2fs 1.42.7 (21-Jan-2013)
Filesystem volume name:   <none>
Last mounted on:          /win
Filesystem UUID:          cd4bf4d2-bc32-4777-a437-ee24c4ee5f1b
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal ext_attr resize_inode dir_index
filetype needs_recovery extent flex_bg sparse_super large_file huge_file
uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash
Default mount options:    user_xattr acl
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              30507008
Block count:              122012416
Reserved block count:     0
Free blocks:              72021328
Free inodes:              30474619
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      994
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8192
Inode blocks per group:   512
RAID stride:              32747
Flex block group size:    16
Filesystem created:       Fri Sep  7 20:44:21 2012
Last mount time:          Thu Apr  4 12:22:01 2013
Last write time:          Thu Apr  4 12:22:01 2013
Mount count:              256
Maximum mount count:      -1
Last checked:             Sat Sep  8 21:13:28 2012
Check interval:           0 (<none>)
Lifetime writes:          1011 GB
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               256
Required extra isize:     28
Desired extra isize:      28
Journal inode:            8
Default directory hash:   half_md4
Directory Hash Seed:      b6ad3f8b-72ce-49d6-92cb-abccd7dbe98e
Journal backup:           inode blocks
Journal features:         journal_incompat_revoke
Journal size:             128M
Journal length:           32768
Journal sequence:         0x00054dc7
Journal start:            8193

> Oh, and what options were you using to when you kicked off
> the VM?

qemu-kvm -k en-us -smp 2 -m 1200 -soundhw hda -usb -usbdevice tablet
-net user -net nic,model=e1000 -serial pty -balloon virtio -hda x.img

> The other thing that would be useful was to enable the jbd2_run_stats
> tracepoint and to send the output of the trace log when you notice the
> interactivity problems.

Ok, I will try.

thanks,
-- 
js
suse labs
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