Re: [PATCH 3/3] compcache documentation

From: Andrew Morton
Date: Sat Mar 21 2009 - 06:32:36 EST


On Fri, 20 Mar 2009 19:44:08 +0530 Nitin Gupta <ngupta@xxxxxxxxxx> wrote:

> ...
>
> + backing_dev: This is block device to be used as backing store for compcache.
> + It must be a valid swap partition. We move data to this device when we
> + encounter incompressible page or memlimit is reached. TODO: we may also
> + move some pages from compcache to this device in case system is really
> + low on memory.
> + This device is not directly visible to kernel as a swap device
> + (/proc/swaps will only show /dev/ramzswap0 and not this device).
> + Managing this backing device is the job of compcache module.

hrm, OK, it kinda/sorta/maybe might be a little bit like a "compressed
cache". But if someone comes up with a real compressed cache (ie:
pagecache) then they'll want their name back.

Also, the kernel already has a widespread and well-established "backing
device" concept, in include/linux/backing-dev.h. This new feature's
poaching of that identifier is a bit confusing. It would be nice to do a
wholesale rename if possible. secondary_dev? nv_dev?

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