With DEBUG_VFS_LOCKS:

real    1m30.660s
user    36m45.705s
sys     4m29.366s

real    1m28.719s
user    36m46.984s
sys     4m28.822s

real    1m28.260s
user    36m44.925s
sys     4m26.699s

real    1m28.465s
user    36m47.688s
sys     4m26.057s

real    1m28.591s
user    36m43.998s
sys     4m27.509s

real    1m29.197s
user    36m50.445s
sys     4m26.136s

real    1m28.458s
user    36m48.276s
sys     4m26.791s

real    1m28.754s
user    36m44.762s
sys     4m27.180s

real    1m29.315s
user    36m46.439s
sys     4m27.361s

real    1m28.761s
user    36m45.966s
sys     4m26.340s

Plain INVARIANTS:

real    1m28.906s
user    36m42.111s
sys     4m25.751s

real    1m28.371s
user    36m43.644s
sys     4m27.116s

real    1m28.058s
user    36m44.385s
sys     4m25.151s

real    1m28.371s
user    36m43.646s
sys     4m27.027s

real    1m28.603s
user    36m42.028s
sys     4m26.214s

real    1m28.661s
user    36m44.375s
sys     4m26.748s

real    1m28.921s
user    36m45.989s
sys     4m26.662s

real    1m28.396s
user    36m45.277s
sys     4m25.670s

real    1m28.271s
user    36m43.424s
sys     4m29.449s

real    1m28.925s
user    36m45.932s
sys     4m26.640s

GENERIC-NODEBUG

real    1m25.090s
user    36m40.387s
sys     2m24.444s

real    1m23.272s
user    36m40.387s
sys     2m21.498s

real    1m23.323s
user    36m38.656s
sys     2m22.923s

real    1m23.069s
user    36m38.164s
sys     2m22.265s

real    1m23.002s
user    36m43.107s
sys     2m21.254s

real    1m23.384s
user    36m42.534s
sys     2m21.091s

real    1m23.263s
user    36m38.766s
sys     2m22.844s

real    1m23.412s
user    36m40.811s
sys     2m23.078s

real    1m23.446s
user    36m39.096s
sys     2m21.509s

real    1m23.029s
user    36m39.845s
sys     2m22.214s