solarflow99 wrote:
Also I don't think touching the default filesystem and it's config is a
good thing here. One can always tune things as needed but the defaults
should be sane.
Simon
I had wondered about this too, the link provided showed a tuning guide
from 1999, it makes me wonder if mounting noatime or chattr +A is
really worth it. I also see ACL's are enabled by default, there's
probably a small penalty for this too, but its so small its likely
unnoticeable anyways.
Newer kernels have relatime as default, which should at least reduce
atime overhead if you're reading the same files over and over. noatime
should still be an improvement, but less than with RHEL 5.
Another thing that, depending on workload, might affect performance
quite a lot is that RHEL 6 by default mounts with barriers enabled, as
was already mentioned in this thread. I predict that this will result in
a lot of performance bugs submitted to RH, lots of mailing list traffic,
plenty of blog posts with varying levels of cluefulness, and so on. ;-)
Too bad RHEL6 missed the recent replacement of block IO barriers with
unsequenced flush/fua requests (queued for 2.6.37) which should remove
the overhead of barriers on devices in write-through caching mode (or
look as such to the kernel, for example array controllers with
battery-backed caches).
--
Janne Blomqvist
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