[Lustre-discuss] Performance drop (1.6.5 vs 1.6.4.3, OFED 1.2)?

[Johann Lombardi]

On Wed, Jul 16, 2008 at 06:26:05PM +0200, Andrei Maslennikov wrote:
> I however worry much more about the case when checksumming is
> disabled. Do you think that the 20% performance drop may also be explained by
> the combination of ([6]1.6.4.1 server / [7]1.6.5.1 client)??

LRU resize is disabled by default in 1.6.4.3 whereas it is enabled in 1.6.5.1.
We have found a problem with this new feature recently (i.e. the LRU shrinking
code is running much too often causing a performance drop):
https://bugzilla.lustre.org/show_bug.cgi?id=17282

You can disable LRU resize in 1.6.5.1 by running the following command on the
lustre clients:
lctl set_param ldlm.namespaces.*osc*.lru_size=$((100 * nbprocs))
(replace nbprocs by the number of CPUs on the node)

Johann