####
## IO Scheduler
####

# First, set an appropriate IO scheduler for file servers.
# deadline - For spinning disks
# noop     - For VMs and SSDs
echo noop > /sys/block/sdX/queue/scheduler

# Now give the IO scheduler more flexibility by increasing the number of schedulable requests:
echo 4096 > /sys/block/sdX/queue/nr_requests

# To improve throughput for sequential reads, increase the maximum amount of read-ahead data.
# The actual amount of read-ahead is adaptive,
# so using a high value here won't harm performance for small random access.
echo 4096 > /sys/block/sdX/queue/read_ahead_kb

####
## Virtual memory settings
####

# To avoid long IO stalls (latencies) for write cache flushing
# in a production environment with very different workloads,
# you will typically want to limit the kernel dirty (write) cache size:
echo 5 > /proc/sys/vm/dirty_background_ratio
echo 10 > /proc/sys/vm/dirty_ratio

# Assigning slightly higher priority to inode caching helps
# to avoid disk seeks for inode loading:
echo 50 > /proc/sys/vm/vfs_cache_pressure

# Decrease swappiness to prevent swapping as much as possible
echo 1 > /proc/sys/vm/swappiness

# Buffering of file system data requires frequent memory allocation.
# Raising the amount of reserved kernel memory will enable faster and more reliable
# memory allocation in critical situations.
# Raise the corresponding value to 64MB if you have less than 8GB of memory,
# otherwise raise it to at least 256MB:
echo 262144 > /proc/sys/vm/min_free_kbytes

# It is recommended to have transparent huge pages disabled:
echo madvise > /sys/kernel/mm/transparent_hugepage/enabled

####
## Process scheduler
####

# There's a kernel parameter that determines how long a migrated process has to be running
# before the kernel will consider migrating it again to another core.
# The sysctl name is sched_migration_cost_ns, default value 50000 (that's ns so 0.5 ms).
# Forking servers, like PostgreSQL or Apache, scale to much higher levels of concurrent
# connections if this is made larger, by at least an order of magnitude:
echo 5000000 > /proc/sys/kernel/sched_migration_cost_ns

# Another parameter that can dramatically impact forking servers is sched_autogroup_enabled.
# This setting groups tasks by TTY, to improve perceived responsiveness on an interactive system.
# On a server with a long running forking daemon, this will tend to keep child processes from
# migrating away as soon as they should.
# It can be disabled like so:
echo 0 > /proc/sys/kernel/sched_autogroup_enabled

####
## CPU
####

# Set the scaling governor to performance. This keeps the CPU at maximum frequency
echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor