RE: [PATCH v2 0/3] staging: zcache: xcfmalloc support

Dan Magenheimer
2011-09-15T22:27:42Z

> 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.