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Date: Thu, 15 Sep 2011 15:27:07 -0700 (PDT)
From: Dan Magenheimer <dan.magenheimer@oracle.com>
To: Dave Hansen <dave@linux.vnet.ibm.com>,
        Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Nitin Gupta <ngupta@vflare.org>, Greg KH <greg@kroah.com>, gregkh@suse.de,
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        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
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Subject: RE: [PATCH v2 0/3] staging: zcache: xcfmalloc support
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> From: Dave Hansen [mailto:dave@linux.vnet.ibm.com]
> Subject: Re: [PATCH v2 0/3] staging: zcache: xcfmalloc support
> 
> On Thu, 2011-09-15 at 14:24 -0500, Seth Jennings wrote:
> > How would you suggest that I measure xcfmalloc performance on a "very
> > large set of workloads".  I guess another form of that question is: How
> > did xvmalloc do this?
> 
> Well, it didn't have a competitor, so this probably wasn't done. :)
> 
> I'd like to see a microbenchmarky sort of thing.  Do a million (or 100
> million, whatever) allocations, and time it for both allocators doing
> the same thing.  You just need to do the *same* allocations for both.

One suggestion:  We already know xvmalloc sucks IF the workload has
poor compression for most pages.  We are looking to understand if xcfmalloc
is [very**N] bad when xvmalloc is good.  So please measure BIG-NUMBER
allocations where compression is known to be OK on average (which is,
I think, a large fraction of workloads), rather than workloads where
xvmalloc already sucks.