A very interesting part of /proc is directory /proc/sys. This is not only a source of information, it also allows you to change parameters within the kernel. Be very careful when attempting this. You can optimize your system, but you can also cause it to crash. Never alter kernel parameters on a production system. Set up a development machine and test to make sure that everything works the way you want it to. You may have no alternative but to reboot the machine once an error has been made.

To change a value, simply echo the new value into the file. You need to be root to do this. You can create your own boot script to perform this every time your system boots.

The files in /proc/sys can be used to fine tune and monitor miscellaneous and general things in the operation of the Linux kernel. Since some of the files can inadvertently disrupt your system, it is advisable to read both documentation and source before actually making adjustments. In any case, be very careful when writing to any of these files.


I would like to see these new sysctl parameters documented for
the new completely fair scheduler in sles11 for example.
Ingo Molnar was then engineer

kernel.sched_min_granularity_ns = 8000000
kernel.sched_latency_ns = 40000000
kernel.sched_wakeup_granularity_ns = 10000000
kernel.sched_shares_ratelimit = 500000
kernel.sched_child_runs_first = 1
kernel.sched_features = 7807
kernel.sched_migration_cost = 500000
kernel.sched_nr_migrate = 32
kernel.sched_rt_period_us = 1000000
kernel.sched_rt_runtime_us = 950000
kernel.sched_compat_yield = 0
kernel.sched_domain.cpu0.domain0.min_interval = 1
kernel.sched_domain.cpu0.domain0.max_interval = 4
kernel.sched_domain.cpu0.domain0.busy_idx = 2
kernel.sched_domain.cpu0.domain0.idle_idx = 0
kernel.sched_domain.cpu0.domain0.newidle_idx = 0
kernel.sched_domain.cpu0.domain0.wake_idx = 1
kernel.sched_domain.cpu0.domain0.forkexec_idx = 1
kernel.sched_domain.cpu0.domain0.busy_factor = 64
kernel.sched_domain.cpu0.domain0.imbalance_pct = 125
kernel.sched_domain.cpu0.domain0.cache_nice_tries = 1
kernel.sched_domain.cpu0.domain0.flags = 559