Date: Sat, 13 May 2000 15:48:08 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Chuck Paterson <cp@bsdi.com> Cc: arch@freebsd.org Subject: Re: A new api for asynchronous task execution Message-ID: <Pine.BSF.4.21.0005131540090.47945-200000@salmon.nlsystems.com> In-Reply-To: <200005131422.IAA00701@berserker.bsdi.com>
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This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. Send mail to mime@docserver.cac.washington.edu for more info. --0-920267420-958229288=:47945 Content-Type: TEXT/PLAIN; charset=US-ASCII On Sat, 13 May 2000, Chuck Paterson wrote: > > Doug, > You might want to consider having a separate function/macro > to enqueue on the taskqueue_swi. Instead of passing in the actual > name of the task queue you would pass in some sort of flag which > for now could be something like TASKQUEUE(foobar, TASKQUEUE_SWI). > This would allow the lower level taskqueue_enqueue to just do the > enqueueing without having to check if a software interrupt needs > to be generated. For now the flag could be totally ignored, adding > zero weight to what you have now. Later on, supposing that the > system can support multiple interrupt threads on multiple processors, > the flag could be used in a switch statement that determines which > level/queue the task gets enqueued on. In a macro this code would > be determined at compile time. Also it may be useful to have a flag > that prevents immediate execution, ie no scheduling event, if the > task is enqueued from the top half. This also is not needed at all > now. I don't want to make the api too specific to one particular method of running the queue (i.e. software interrupts). The intention is that the taskqueue_xxx() apis simply deal with moving tasks onto and off the queue. The system defines specific implementations of queues which are drained at particular times (initially I have defined one using SWI). I want to make it as easy as possible to define different lightweight queues for various types of work. The 'enqueue' function pointer in the taskqueue structure defines the run policy for the queue. I can imagine various queues being written which drain at different times (e.g. on clock tick, once after autoconfiguration, driver-specific work queues etc.) Take a look at my initial implementation to see how taskqueue_swi is implemented. Note that the implementation of taskqueue_swi is logically separate from the taskqueue api itself. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. 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