Re: [PATCHv13 3/4] zswap: add to mm/

From: Bob Liu
Date: Wed Jun 19 2013 - 10:17:25 EST

On Wed, Jun 19, 2013 at 10:09 PM, Seth Jennings
<sjenning@xxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Jun 17, 2013 at 02:20:05PM +0800, Bob Liu wrote:
>> Hi Seth,
>> On Tue, Jun 4, 2013 at 4:33 AM, Seth Jennings
>> <sjenning@xxxxxxxxxxxxxxxxxx> wrote:
>> > zswap is a thin backend for frontswap that takes pages that are in the process
>> > of being swapped out and attempts to compress them and store them in a
>> > RAM-based memory pool. This can result in a significant I/O reduction on the
>> > swap device and, in the case where decompressing from RAM is faster than
>> > reading from the swap device, can also improve workload performance.
>> >
>> > It also has support for evicting swap pages that are currently compressed in
>> > zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a
>> > true cache in that, once the cache is full, the oldest pages can be moved out
>> > of zswap to the swap device so newer pages can be compressed and stored in
>> > zswap.
>> >
>> > This patch adds the zswap driver to mm/
>> >
>> Do you have any more benchmark can share with me ? To figure out that
>> we can benefit from zswap.
> The two I've done or kernbench and SPECjbb. I'm trying out the memtests

Thanks, I'll try to setup them.

> now. I'd like to be able to explain the numbers you are seeing at least.
> Sorry for the delay. I'll get back to you once I've figured out how
> to using mmtests and get some results/explanations.
> Also, how much physical RAM did this box have? I see 2G in the profile name
> but not sure if that is the workload size or the RAM size. I seems that the

2G RAM size.

> test is overcommitted from the beginning as indicated by the swap activity.
> I know that the parallelio-memcachetest default profile only uses 80% of
> physical memory, so you have apparently made a change yes?

No, I just "cp configs/config-global-dhp__parallelio-memcachetest
config" and then run with monitor.
I'm using mmtests version 0.10.

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