diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/padata.txt | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/Documentation/padata.txt b/Documentation/padata.txt index 7ddfe216a0aa..b103d0c82000 100644 --- a/Documentation/padata.txt +++ b/Documentation/padata.txt @@ -1,5 +1,8 @@ +======================================= The padata parallel execution mechanism -Last updated for 2.6.36 +======================================= + +:Last updated: for 2.6.36 Padata is a mechanism by which the kernel can farm work out to be done in parallel on multiple CPUs while retaining the ordering of tasks. It was @@ -9,7 +12,7 @@ those packets. The crypto developers made a point of writing padata in a sufficiently general fashion that it could be put to other uses as well. The first step in using padata is to set up a padata_instance structure for -overall control of how tasks are to be run: +overall control of how tasks are to be run:: #include <linux/padata.h> @@ -24,7 +27,7 @@ The workqueue wq is where the work will actually be done; it should be a multithreaded queue, naturally. To allocate a padata instance with the cpu_possible_mask for both -cpumasks this helper function can be used: +cpumasks this helper function can be used:: struct padata_instance *padata_alloc_possible(struct workqueue_struct *wq); @@ -36,7 +39,7 @@ it is legal to supply a cpumask to padata that contains offline CPUs. Once an offline CPU in the user supplied cpumask comes online, padata is going to use it. -There are functions for enabling and disabling the instance: +There are functions for enabling and disabling the instance:: int padata_start(struct padata_instance *pinst); void padata_stop(struct padata_instance *pinst); @@ -48,7 +51,7 @@ padata cpumask contains no active CPU (flag not set). padata_stop clears the flag and blocks until the padata instance is unused. -The list of CPUs to be used can be adjusted with these functions: +The list of CPUs to be used can be adjusted with these functions:: int padata_set_cpumasks(struct padata_instance *pinst, cpumask_var_t pcpumask, @@ -71,12 +74,12 @@ padata_add_cpu/padata_remove_cpu are used. cpu specifies the CPU to add or remove and mask is one of PADATA_CPU_SERIAL, PADATA_CPU_PARALLEL. If a user is interested in padata cpumask changes, he can register to -the padata cpumask change notifier: +the padata cpumask change notifier:: int padata_register_cpumask_notifier(struct padata_instance *pinst, struct notifier_block *nblock); -To unregister from that notifier: +To unregister from that notifier:: int padata_unregister_cpumask_notifier(struct padata_instance *pinst, struct notifier_block *nblock); @@ -84,7 +87,7 @@ To unregister from that notifier: The padata cpumask change notifier notifies about changes of the usable cpumasks, i.e. the subset of active CPUs in the user supplied cpumask. -Padata calls the notifier chain with: +Padata calls the notifier chain with:: blocking_notifier_call_chain(&pinst->cpumask_change_notifier, notification_mask, @@ -95,7 +98,7 @@ is one of PADATA_CPU_SERIAL, PADATA_CPU_PARALLEL and cpumask is a pointer to a struct padata_cpumask that contains the new cpumask information. Actually submitting work to the padata instance requires the creation of a -padata_priv structure: +padata_priv structure:: struct padata_priv { /* Other stuff here... */ @@ -110,7 +113,7 @@ parallel() and serial() functions should be provided. Those functions will be called in the process of getting the work done as we will see momentarily. -The submission of work is done with: +The submission of work is done with:: int padata_do_parallel(struct padata_instance *pinst, struct padata_priv *padata, int cb_cpu); @@ -138,7 +141,7 @@ need not be completed during this call, but, if parallel() leaves work outstanding, it should be prepared to be called again with a new job before the previous one completes. When a task does complete, parallel() (or whatever function actually finishes the job) should inform padata of the -fact with a call to: +fact with a call to:: void padata_do_serial(struct padata_priv *padata); @@ -151,7 +154,7 @@ pains to ensure that tasks are completed in the order in which they were submitted. The one remaining function in the padata API should be called to clean up -when a padata instance is no longer needed: +when a padata instance is no longer needed:: void padata_free(struct padata_instance *pinst); |