[linux-mm-cc] Question using compacache(zram) with multi devices

[Mike Cao]

On Thu, 2010-12-23 at 15:16 +0800, John McCabe-Dansted wrote:
> On Thu, Dec 23, 2010 at 2:48 PM, Mike Cao <bcao at redhat.com> wrote:
> > Scenario 1:
> > 1.Initialize TWO zram devices with 100MB each.
> ...
> > Scenario 2:
> > 1.Initialize ONE zram devices with 200MB
> ...
> > Both of scenarios,I can find 200MB swap new added.then What's the
> > difference between the two scenarios ,especially for performance
> > influence?
> 
> Probably not much. I imagine the main difference is that in Scenario 1
> you can adjust the amount of compcache more easily as you have the
> option of disabling one of the two 100MB swap devices.
Hi ,I also think so.

Please look at http://code.google.com/p/compcache/wiki/zcacheIOzone ,the
last 2 items in details.
	*Separate partitions (all ext4) for: /boot, / and /home. So, three
separate zcache pools
	*Each pool with default memlimit: 10% of RAM (memory is allocated
on-demand and is not pre-allocated)

I wonder whether the /dev/zramX means zcache pools ?if it is ,why need
three?

> 
> Presumably Scenario 1 uses up a little more memory. It may also reduce
> lock contention slightly on machines with lots of cores, but I am not
> familiar enough with the code to know if that is the case.
> 

-- 

Best Regards!
Mike