Comment 323 for bug 131094

Unfortunately, this does not seem to be the case on my ThinkPad X61. I
did not see any noticeable difference between writeback and ordered
mode. With writeback, interactivity is still sluggish during disk
writes. Applications hang, interfaces slow to respond etc. So clearly
this cannot be the main issue...

- Johannes

On Wed, Jun 23, 2010 at 10:18 PM, Johannes H. Jensen
<email address hidden> wrote:
> So I just tested writeback on my desktop computer which exhibits the
> same problems. I mounted both the root filesystem and /home with
> data=writeback (ext3).
>
> So far the difference is *huge*! The system is much more responsive -
> I'm writing this while 'stress -d 4' is running in the background. The
> same applies to the dd test - all apps respond almost instantly with
> writeback, as opposed to sluggish and hanging with ordered.
> Applications open much faster as well....
>
> I'll do some more testing to confirm - mainly writeback only on /home
> vs root and also on my laptop. Is this a bug in ext3 then, or is
> ordered mode supposed to be so slow / problematic on desktop systems?
> What problems might occur when using writeback mode? I'm a bit
> concerned about the following comment from the mount manual:
>
> It  guarantees  internal  filesystem integrity,  however  it  can
> allow old data to appear in files after a crash and journal recovery.
>
> By the way, to use writeback on the root filesystem, setting
> data=writeback in fstab only is not sufficient. As 'man mount' states:
>
> To use modes other than ordered on  the  root filesystem,  pass the
> mode to the kernel as boot parameter, e.g. rootflags=data=journal.
>
> - Johannes
>
>
> On Wed, Jun 23, 2010 at 11:52 AM, Johannes H. Jensen
> <email address hidden> wrote:
>> I haven't tried writeback, no. Is it possible to remount with this
>> option, or do I need to modify fstab and reboot?
>>
>> - Johannes
>>
>>
>> On Wed, Jun 23, 2010 at 10:00 AM, Peter Hoeg <email address hidden> wrote:
>>> Have you tried mounting the filesystems with writeback instead of
>>> ordered?
>>>
>>> /peter
>>>
>>> On Wed, Jun 23, 2010 at 15:42, Johannes H. Jensen <email address hidden> wrote:
>>>> I just tested with the anticipatory scheduler on the stock Ubuntu
>>>> 2.6.32:
>>>>
>>>> # echo anticipatory > /sys/block/sda/queue/scheduler
>>>>
>>>> This did not seem to have any effect - the problem was still very much
>>>> present.
>>>>
>>
>