This blog contains some notes that I have made in respect to the best practices inorder to get the best performance from IBM Java in IBM POWER Linux. More information about further tuning in relation to Linux and Java can be found at the POWERLinux Community under the article 'Java Performance on POWER7'.
My Recommendations are :
1. Turning off Hardware data prefetch with the Linux command "ppc64_cpu --dscr=1 "
2. The default page size is 64 KB page size, this will normally provide good performance gains over 4 KB pages. For possible performance gains, enable 16 MB page size -
# cat /proc/meminfo
3. Most of the time the best performance if from 32-bit Java, that issunless the memory requirement of the application requires you to be running in 64-bit mode. Make sure libgcc.ppc and glibc.ppc are installed else the 32bit java won't have the right libraries.
/root/.bashrc - has the path in this case to set the profile to which version of java 32 or 64 bit to be used
4. Most applications benefit from SMT. However, some applications do not scale with an increased number of logical CPUs on an SMT enabled system. One way to address such an application scalability issue is to change to a lower SMT mode with fewer logical CPUs; for examples, changing from SMT4 to SMT2. Details of how to set your SMT mode can be found 'HERE'
Disclaimer - Your mileage will vary
All performance data contained in this blog was obtained in a specific operating environment and under set conditions so is presented as an example. Performance obtained in other operating environments may vary and customers should conduct their own testing.