After nearly 2 years I have received an answer for my inquiry.
The problems appear to have been corrected and the project has been moved to:
https://github.com/google/gipfeli
Initial results in fsbench on core2:
Note that gipfeli has an API based on std::string that doesn't match well to what fsbench expects and requires my adaptation layer to do memcpy back and forth. A project designed to use gipfeli would have better performance to what I show below. Also, fsbench is compiled with SSE2 and intel-zlib's special quick mode is enabled (unlike in what I've shown before).
Code:
katmacadapc% ./fsbench zlib,1 shrinker gipfeli miniz,1 quicklz,2 files/_FOSSIL_
Codec version args
C.Size (C.Ratio) E.Speed D.Speed E.Eff. D.Eff.
zlib 2014-06-16 Intel 1
144872 (x 6.877) 91.0 MB/s 359 MB/s 77e6 306e6
Shrinker r6
169186 (x 5.889) 293 MB/s 802 MB/s 243e6 665e6
gipfeli 2014-06-30
188905 (x 5.274) 221 MB/s 432 MB/s 179e6 350e6
miniz 1.11 1
154118 (x 6.465) 186 MB/s 306 MB/s 157e6 258e6
QuickLZ 1.5.1b6 2
158442 (x 6.288) 170 MB/s 416 MB/s 143e6 350e6
Codec version args
C.Size (C.Ratio) E.Speed D.Speed E.Eff. D.Eff.
done... (4*X*1) iteration(s)).
katmacadapc% ./fsbench zlib,1 shrinker gipfeli miniz,1 quicklz,2 files/scc1.tar
Codec version args
C.Size (C.Ratio) E.Speed D.Speed E.Eff. D.Eff.
zlib 2014-06-16 Intel 1
5829409 (x 2.161) 38.5 MB/s 162 MB/s 20e6 86e6
Shrinker r6
6691068 (x 1.882) 144 MB/s 570 MB/s 67e6 267e6
gipfeli 2014-06-30
6244270 (x 2.017) 124 MB/s 250 MB/s 62e6 125e6
miniz 1.11 1
6245122 (x 2.017) 73.7 MB/s 136 MB/s 37e6 68e6
QuickLZ 1.5.1b6 2
6141358 (x 2.051) 90.5 MB/s 162 MB/s 46e6 82e6
Codec version args
C.Size (C.Ratio) E.Speed D.Speed E.Eff. D.Eff.
done... (4*X*1) iteration(s)).
katmacadapc% ./fsbench zlib,1 shrinker gipfeli miniz,1 quicklz,2 files/calgary.tar
Codec version args
C.Size (C.Ratio) E.Speed D.Speed E.Eff. D.Eff.
zlib 2014-06-16 Intel 1
1281280 (x 2.549) 37.5 MB/s 158 MB/s 22e6 95e6
Shrinker r6
1540611 (x 2.120) 133 MB/s 501 MB/s 70e6 264e6
gipfeli 2014-06-30
1387112 (x 2.355) 117 MB/s 201 MB/s 67e6 115e6
miniz 1.11 1
1425257 (x 2.292) 70.0 MB/s 123 MB/s 39e6 69e6
QuickLZ 1.5.1b6 2
1354211 (x 2.412) 87.7 MB/s 170 MB/s 51e6 99e6
Codec version args
C.Size (C.Ratio) E.Speed D.Speed E.Eff. D.Eff.
done... (4*X*1) iteration(s)).
Overall, it's a pareto frontier, but I expected more.