RE: [PATCH part2 v6 0/3] staging: zcache: Support zero-filled pages more efficiently

[Dan Magenheimer <dan.magenheimer@oracle.com>]

> From: Wanpeng Li [mailto:liwanp@linux.vnet.ibm.com]
> Subject: Re: [PATCH part2 v6 0/3] staging: zcache: Support zero-filled pages more efficiently
> 
> Hi Dan,
> 
> Some issues against Ramster:
> 
> - Ramster who takes advantage of zcache also should support zero-filled
>   pages more efficiently, correct? It doesn't handle zero-filled pages well
>   currently.

When you first posted your patchset I took a quick look at ramster
and it looked like your patchset should work for ramster also.
However I didn't actually run ramster to try it so there may
be a bug.  If it doesn't work, I would very much appreciate a patch.

> - Ramster DebugFS counters are exported in /sys/kernel/mm/, but zcache/frontswap/cleancache
>   all are exported in /sys/kernel/debug/, should we unify them?

That would be great.

> - If ramster also should move DebugFS counters to a single file like
>   zcache do?

Sure!  I am concerned about Konrad's patches adding debug.c as they
add many global variables.  They are only required when ZCACHE_DEBUG
is enabled so they may be ok.  If not, adding ramster variables
to debug.c may make the problem worse.

> If you confirm these issues are make sense to fix, I will start coding. ;-)

That would be great.  Note that I have a how-to for ramster here:

https://oss.oracle.com/projects/tmem/dist/files/RAMster/HOWTO-120817 

If when you are testing you find that this how-to has mistakes,
please let me know.  Or feel free to add the (corrected) how-to file
as a patch in your patchset.

Thanks very much, Wanpeng, for your great contributions!

(Ric, since you have expressed interest in ramster, if you try it and
find corrections to the how-to file above, your input would be
very much appreciated also!)

Dan

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