• Performance tuning is... Before you begin How much is how much? Calculating unit conversions Monitoring Monitoring vs. Profiling Whole-system view Sample application model Sample hardware model Before tuning the kernel Kernel tunables Using system documentation Recovering from problems

• SNMP SNMP versions Management Information Base The MIB hierarchy Referring to MIB objects Reading a MIB file Installing SNMP packages Finding MIB objects Using SNMP v1 for queries Using SNMP v3 for queries Configuring the SNMP client Enabling the SNMP agent Profiling SNMP host access controls Configuring SNMP v1 access Configuring SNMP v3 access Beyond RH442: Extending snmpd

• MRTG Configuring MRTG Allowing access to MRTG Creating a dashboard in MRTG Ad-hoc utilities Installing iostat and sar Using iostat and sar Configuring sar Awk Using awk Gnuplot Using Gnuplot Creating a custom script Scheduling a custom script

• OProfile Installing OProfile Installing kernel-debuginfo Setting up OProfile Running a test Reviewing results OProfile architecture SystemTap Required packages SystemTap scripts The stap command

• Introduction to queuing theory Little's Law Queue length Queue length vs wait time Wait time A closer look at wait time How much user time is needed? Profiling time with time Finding hot spots in code Completion rate Arrival rate vs completion rate Finding a valid observation period Predicting system-wide limits Predicting resource limits Summary of strategies

• Physical factors affect disk IO Disk storage density Choosing a peripheral interconnect SCSI bus considerations Electro-mechanical positioning Block IO requests and cache effect Tuning sequential read access Tuning the disk queue Tuning the deadline scheduler Tuning the anticipatory scheduler Tuning the noop scheduler Tuning the (default) cfq scheduler Fine-tuning the cfq scheduler Physical block device interfaces Virtual block devices Tuning virtual block devices Logical volumes and VBDs Implementing snapshot storage

• The virtual file system (VFS) Layout of ext2/ext3 Fragmentation Viewing fragmentation Tuning fragmentation Filesystem limits Journaling Improving journal performance Tuning journal placement Other mount-time options Finding lock contention Reducing visit count with RAID Calculating chunk size Calculating filesystem stride Tuning round-robin RAID Write overhead for RAID5 and RAID6 Improving RAID1 performance Tuning RAID1 Tuning RAID in SysFS

• Characterizing process states Getting ready to run Types of CPU cache Locality of reference Improving locality of reference Multitasking and the run queue Preempting the current process Sorting the run queue SCHED_OTHER Tuning scheduler policy Viewing CPU performance data

• How Linux tracks time Tuning system ticks Tuning processor speed IRQ balancing Tuning IRQ affinity Equalizing CPU visit count Tuning process affinity with taskset Tuning run queue length with taskset Hot-plugging CPUs Scheduler domains Configuring the root cpuset Configuring a child cpuset Important files for scheduler domains Virtual CPUs Tuning VCPUs at domain creation Tuning VCPUs dynamically Tuning VCPU affinity

• Overview of memory addressing Virtual address space (32-bit) Viewing process address space Tuning process address space Physical address space Mapping virtual addresses (x86) Uniform memory architecture (x86) Overview of memory allocation Improving RAM performance Improving MMU performance Tuning the NUMA allocator Improving TLB performance Tuning TLB performance Viewing system calls Virtual domain memory Tuning memory at domain creation Tuning domain memory dynamically Recovering unassigned memory

• Strategies for using memory A closer look at demand paging Tuning page allocation Tuning overcommit Slab cache ARP cache Tuning ARP cache Page cache Tuning page cache Anonymous pages SysV IPC Tuning SysV IPC Viewing memory with free Other commands to view memory usage

• Characterizing page status Calculating dirty and clean memory Reclaiming dirty pages Tuning pdflush Reclaiming clean pages Out-of-memory killer Tuning OOM policy Detecting memory leaks What is swap? Improving swap performance Tuning swappiness Tuning swap size Tuning swap for think time Tuning swap visit count Monitoring memory usage

• Simplified transmit model Simplified receive model Kernel socket buffers Calculating total buffer size Calculating per-socket buffer size Tuning core buffer size Tuning TCP buffer size Tuning DMA buffer size Is packet fragmentation a problem? Tuning fragmentation buffers Network interrupt handling Improving interrupt handling Tuning interrupt handling Network sockets TCP sockets Viewing network sockets Tuning TCP socket creation Tuning TCP socket keepalive

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