Re: Memory pressure handling with iSCSI

[Badari Pulavarty <pbadari@us.ibm.com>]

On Tue, 2005-07-26 at 16:07 -0700, Andrew Morton wrote:
> Badari Pulavarty <pbadari@us.ibm.com> wrote:
> >
> > Here is the data with 5 ext2 filesystems. I also collected /proc/meminfo
> > every 5 seconds. As you can see, we seem to dirty 6GB of data in 20
> > seconds of starting the test. I am not sure if its bad, since we have
> > lots of free memory..
> 
> It's bad.  The logic in balance_dirty_pages() should block those write()
> callers as soon as we hit 40% dirty memory or whatever is in
> /proc/sys/vm/dirty_ratio.  So something is horridly busted.
> 
> Can you try reducing the number of filesystems even further?

Single ext2 filesystem. We still dirty pretty quickly (data collected
every 5 seconds).

 # grep Dirty OUT
Dirty:             312 kB
Dirty:         1121852 kB
Dirty:         2896952 kB
Dirty:         4344564 kB
Dirty:         5310856 kB
Dirty:         5507812 kB
Dirty:         5714884 kB
Dirty:         5865132 kB
Dirty:         6004276 kB
Dirty:         6206544 kB
Dirty:         6380524 kB
Dirty:         6583200 kB
Dirty:         6727296 kB
Dirty:         6708564 kB
Dirty:         6733768 kB
Dirty:         6737868 kB

Thanks,
Badari

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