Re: [PATCH] Page writeback broken after resume: wb_timer lost

[Mark Lord <lkml@rtr.ca>]

Andrew Morton wrote:
> On Tue, 20 Jun 2006 23:38:57 -0400
> Mark Lord <lkml@rtr.ca> wrote:
> 
>>> I just gave it a try here.  With or without a suspend/resume cycle after 
>>> boot,
>>> the "sync" time is much quicker.  But the Dirty count in /proc/meminfo
>>> still shows very huge (eg. 600MB) values that never really get smaller
>>> until I type "sync".  But that subsequent "sync" only takes a couple
>>> of seconds now, rather than 10-20 seconds like before.
>> ..
>>
>> Yup, behaviour is *definitely* much better now.  I'm not sure why
>> the /proc/meminfo "Dirty" count lags behind reality, but the disk
>> is being kept much more up-to-date than without this patch.
> 
> Are you able to come up with a foolproof set of steps which would allow the
> laggy-dirtiness to be reproduced by yours truly?

Heh.. don't I wish!

The best is still as described originally:

http://lkml.org/lkml/2006/2/6/170

Basically, "cat" a ton of huge files together into a single new one,
and then watch /proc/meminfo to see what happens.  For me, the count
there still just hangs at some big number like 500MB until I type "sync",
at which point it (nearly) instantly now goes to zero.

Previous to this patch, the "sync" actually resulted in a ton of disk writes,
but now those happen on the tail end of the "cat" command, as they should.

My kernel .config is available from http://rtr.ca/dell_i9300/kernel/latest/

Cheers