[Lustre-discuss] strange performance with POSIX file capabilities

[Ralf Utermann]

Dear list,

with newer vanilla kernels we  saw strange performance
data with iozone on patchless clients: some OSTs had a lower write
bandwith in the iozone benchmark, getting worse with record
sizes below 1024.
After lots of kernel builds, it looks like the kernel config entry
CONFIG_SECURITY_FILE_CAPABILITIES is the one, wich
introduces this problem. If CONFIG_SECURITY_FILE_CAPABILITIES
is not set, iozone data look good, if it's compiled into the
kernel, we see the problem:
http://www.physik.uni-augsburg.de/~ralfu/LustreTest/Lustre_with_file_caps.html

Any idea, why file capabilities should affect the write
performance on Lustre, and why it should only affect some OSTs?

bye, Ralf
-- 
        Ralf Utermann
_____________________________________________________________________
        Universität Augsburg, Institut für Physik   --   EDV-Betreuer
        Universitätsstr.1             
        D-86135 Augsburg                     Phone:  +49-821-598-3231
        SMTP: Ralf.Utermann at Physik.Uni-Augsburg.DE         Fax: -3411