> I wonder why. Which fs was it?
That was on ext2. There isn't much i/o on autoconf "make check".
It's a lot of small perl scripts, m4 and gcc on tiny files.
>> On the AIM7 database test, -mm2 was about 18% faster and
> iirc, AIM7 is dominated by lots of O_SYNC writes. I'd have expected the
> anticipatory scheduler to do worse. Odd. Which fs was it?
That was ext2 too.
> tiobench will create a bunch of processes, each growing a large file, all
> in the same directory.
> The benchmark is hitting a pathologoical case. Yeah, it's a problem, but
> it's not as bad as tiobench indicates.
Oracle doing reads/writes to preallocated, contiguous files is more
important than tiobench. Oracle datafiles are typically created
sequentially, which wouldn't exercise the pathology.
I pay more attention the OSDL-DBT-3 and "Winmark I" numbers than
the i/o stuff I run. (I look at my numbers more, but care about
theirs more).
What about the behavior where CPU utilization goes down as thread
count goes up? Is she just i/o bound?
Sequential Reads ext2
Num
Kernel Thr Rate (CPU%)
---------- --- ----- ------
2.5.68 8 36.65 18.04%
2.5.68-mm2 8 23.96 11.15%
2.5.68 256 34.10 16.88%
2.5.68-mm2 256 18.84 8.96%
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