Brocade Adapters Troubleshooting Guide 11353-1002145-01Chapter4Performance OptimizationIn this chapter• Tuning storage drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113• Tuning network drivers (CNA or NIC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116Tuning storage driversThis section provides resources for optimizing performance in adapters by tuning the unifiedstorage drivers on Linux, Windows, Solaris, and VMware systems. To optimize performance forCNAs and Fabric Adapter ports configured in CNA or NIC mode, also use resources under “Tuningnetwork drivers (CNA or NIC)” on page 116.Linux tuningLinux disk I/O scheduling reorders, delays, and merges requests to achieve better throughput andlower latency than would happen if all the requests were sent straight to the disk. Linux 2.6 hasfour different disk I/O schedulers: noop, deadline, anticipatory and completely fair queuing.Enabling the “noop” scheduler avoids any delays in queuing of I/O commands. This helps inachieving higher I/O rates by queuing multiple outstanding I/O requests to each disk.To enable the noop scheduler, run the following commands on your system.for i in /sys/block/sd[b-z]/queue/schedulerdoecho noop > $idoneNOTEYou must disable the default scheduler because it is not tuned for achieving the maximum I/Operformance.For performance tuning on Linux, refer to the following publications:• Workload Dependent Performance Evaluation of the Linux 2.6 IO SchedulersHeger, D., Pratt, S., Linux Symposium, Ottawa, Canada, July 2004• Optimizing Linux PerformanceHP Professional Books, ISBN: 0-13-148682-9• Performance Tuning for Linux ServersSandra K. Johnson, Gerrit Huizenga, Badari Pulavarty, IBM Press, ISBN: 013144753X• Linux Kernel Development
