[Plugin: WP Super Cache] Version 0.9.9.9 object cache support

I have WP 3.0.5, HyperDB, memcache and the wp-total-cache plugin installed without caching the database. I decided to install the latest version of wp-super-cache 0.9.9.9 which has an experimental object cache support to check if it was going to work on my environment.

Things seams to be caching well in memcache (hits and amount of data) but when I try to benchmark the performance of the page it shows me that there is something with it.

This is what I get from Apache’s Benchmark:

# ab -c 10 -n 100 URL

Without any caching system: 29.00 Requests per second
W3-total-cache without database caching: 603.76 Requests per second
wp-super-cache without object cache (disk caching): 983.00 Requests per second
wp-super-cache with object cache: 26.55 Requests per second

and http_load tests…

WP Super Cache WITH OBJECT CACHE

# http_load -parallel 10 -fetches 100 urls.txt
100 fetches, 10 max parallel, 3.5979e+06 bytes, in 4.17401 seconds
35979 mean bytes/connection
23.9578 fetches/sec, 861976 bytes/sec
msecs/connect: 0.41752 mean, 10.273 max, 0.125 min
msecs/first-response: 403.312 mean, 795.193 max, 207.813 min
HTTP response codes:
code 200 — 100

WP Super Cache WITHOUT OBJECT CACHE

# http_load -parallel 10 -fetches 100 urls.txt
100 fetches, 10 max parallel, 3.58607e+06 bytes, in 0.097215 seconds
35860.7 mean bytes/connection
1028.65 fetches/sec, 3.6888e+07 bytes/sec
msecs/connect: 0.43917 mean, 2.34 max, 0.123 min
msecs/first-response: 7.25407 mean, 16.934 max, 2.825 min
HTTP response codes:
code 200 — 100

I believe that there is something wrong in my configuration but I am not sure. I have the following check box marked in the plugin configuration:

Caching:
X Cache hits to this website for quick access. (Recommended)
X Use PHP to serve cache files

Miscellaneous:
X Compress pages so they’re served more quickly to visitors. (Recommended)
X Cache rebuild. Serve a supercache file to anonymous users while a new file is being generated. (Recommended)

Advanced:
X Mobile device support.
X Use object cache to store cached files. (Experimental)

and I get this at the bottom of the page source:

<!– Dynamic page generated in 0.163 seconds. –>
<!– Cached page generated by WP-Super-Cache on 2011-04-18 17:03:37 –>
<!– Compression = gzip –>

Is there anything that has to be done in order to get the object cache support for wp-super-cache working?

Thanks!