ZFS arc_reclaim_needed: better cooperation with pagedaemon

[jhell]

On 08/23/2010 22:10, Artem Belevich wrote:
> First prepare the data.
> * You'll need some files totalling around the amount of physical
> memory on your box.  Multiple copies of /usr/src should do the trick.
> * Place one copy on UFS filesystem and another on ZFS
> 
> Experiment #1:
> * Prime ARC by tarring dataset on ZFS into /dev/null.
> * Now tar both datasets in parallel with output to /dev/null
> 
> Previously you would end up with ARC size shrinking down to arc_min.
> What I hope to see after the patch is that inactive memory and ARC
> reach some sort of equilibrium with neither monopolizing all available
> memory.
> 
> #Experiment #2:
> If equilibrium is reached, try running some application that would
> allocate and use about 1/2 of your physical memory.
> Something like that perl one-liner used to cause memory shortage, only
> a bit less drastic.
> perl -e '$x="x"x1_000_000_000';   # this should allocate about 2GB.
> Tune the number to suit your system.
> 
> Again, in the past ARC would be the one feeing up the memory. Let's
> see if inactive list gives up some, too.

Alright I should be able to have something together with the output of
this by the 25th with my current workload being the ultimate determining
factor.

PBS, Regards,

-- 

 jhell,v