2.4.19pre9aa2

Comparing 2.4.19pre8aa3 and 2.4.19pre9aa2 on quad Xeon:
Both kernels configured with CONFIG_2GB=y and CONFIG_HIGHIO=y.

dbench 64/192 on various filesystems had a 2-20% improvement. (average 5 runs).

tbench 192 throughput up over 300%.

LMBench pipe bandwidth and latency improved.

The regression in OSDB aggregate simple report compared to non-aa kernels is gone.

More benchmarks on quad Xeon at:
http://home.earthlink.net/~rwhron/kernel/bigbox.html

Randy Hron

very cool work as usual :). Many thanks.

Just a note, watch the "File & VM system latencies in microseconds" lmbench results, the creat become significantly slower, I'm wondering if that's due the removal of the negative dcache after unlink. I think it's still a global optimization (infact I think some of the dbench records are also thanks to maximzing the useful cache information by dropping immediatly negative dentries after unlink), but I wonder if the benchmark is done in a way that generate false positives. To avoid false positives and to really benchmark the whole "creat" path (that includes in its non-cached form also a lookup in the lowlevel fs) lmbench should rmdir; mkdir the directory where it wants to make the later creats (rmdir/mkdir cycle will drop negative dentries in all 2.[245] kernels too). Otherwise at the moment I'm unsure what made creat slower between pre8aa3 and pre9aa2, could it be a fake result of the benchmark? Maybe you could give it a second spin just in case. The pipe bandwith reported by lmbench in pre9aa2 is also very impressive, that's Mike's patch and I think it's also a very worthwhile optimizations since many tasks really uses pipes to passthrough big loads of data.

Andrea