diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/kernel-locking.tmpl | 25 | ||||
| -rw-r--r-- | Documentation/cpu-freq/governors.txt | 8 |
2 files changed, 25 insertions, 8 deletions
diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 77c42f40be5d..2510763295d0 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -703,6 +703,31 @@ </sect1> </chapter> +<chapter id="trylock-functions"> + <title>The trylock Functions</title> + <para> + There are functions that try to acquire a lock only once and immediately + return a value telling about success or failure to acquire the lock. + They can be used if you need no access to the data protected with the lock + when some other thread is holding the lock. You should acquire the lock + later if you then need access to the data protected with the lock. + </para> + + <para> + <function>spin_trylock()</function> does not spin but returns non-zero if + it acquires the spinlock on the first try or 0 if not. This function can + be used in all contexts like <function>spin_lock</function>: you must have + disabled the contexts that might interrupt you and acquire the spin lock. + </para> + + <para> + <function>mutex_trylock()</function> does not suspend your task + but returns non-zero if it could lock the mutex on the first try + or 0 if not. This function cannot be safely used in hardware or software + interrupt contexts despite not sleeping. + </para> +</chapter> + <chapter id="Examples"> <title>Common Examples</title> <para> diff --git a/Documentation/cpu-freq/governors.txt b/Documentation/cpu-freq/governors.txt index 6a9c55bd556b..dcec0564d040 100644 --- a/Documentation/cpu-freq/governors.txt +++ b/Documentation/cpu-freq/governors.txt @@ -129,14 +129,6 @@ to its default value of '80' it means that between the checking intervals the CPU needs to be on average more than 80% in use to then decide that the CPU frequency needs to be increased. -sampling_down_factor: this parameter controls the rate that the CPU -makes a decision on when to decrease the frequency. When set to its -default value of '5' it means that at 1/5 the sampling_rate the kernel -makes a decision to lower the frequency. Five "lower rate" decisions -have to be made in a row before the CPU frequency is actually lower. -If set to '1' then the frequency decreases as quickly as it increases, -if set to '2' it decreases at half the rate of the increase. - ignore_nice_load: this parameter takes a value of '0' or '1'. When set to '0' (its default), all processes are counted towards the 'cpu utilisation' value. When set to '1', the processes that are |