Re: 67-mjb2 vs 68-mjb1 (sdet degredation)

[Martin J. Bligh]

> Yeah, that fixes it. Ho hum ... I wonder if we can find something that
> works well for both cases? I guess the options would be:
> 
> 1. Some way to make the rwlock mechanism itself faster.
> 2. Try to fix the contention itself somehow for this instance.
> 
> Not sure if 1 is fundamentally futile or not, but would obviously be
> better (more general) if it's possible ;-)

Hmmm. Actually seems like more of a "which test you pick" thing than a
machine thing. Maybe it's the balance of read / write accesses to the
rwlock that matters, or something.

time dd if=/dev/zero of=foo bs=1 count=1M

with backout:

real    0m4.302s
user    0m0.900s
sys     0m3.370s

With patch: 

real    0m4.016s
user    0m0.810s
sys     0m3.200s

So the patch helps that test at least. 

M.