From: Erik W. <ome...@us...> - 2000-11-21 21:59:22
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/11/21 13:59:21 gstreamer/docs/design Update of /cvsroot/gstreamer/gstreamer/docs/design In directory slayer.i.sourceforge.net:/tmp/cvs-serv15767/design Log Message: Directory /cvsroot/gstreamer/gstreamer/docs/design added to the repository |
From: Erik W. <ome...@us...> - 2000-11-23 08:13:44
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/11/23 00:13:43 Modified files: gst : gstbin.c gstelement.c Log message: gstbin.c: modified so create_plan occurs after the state change of all the child elements. gstelement.c: set_state now loops such that each element only deals with one state change at a time, i.e. NULL->READY,READY->PLAYING, instead of a single NULL->PLAYING. |
From: Erik W. <ome...@us...> - 2000-11-23 20:39:54
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/11/23 12:39:54 Modified files: gst : gstelement.c Log message: Closed task 22143 - gstelemnt.c: complete gst_element_connect SImple matter of cleaning up the conflicting checks and actually connecting the pads in question. |
From: Erik W. <ome...@us...> - 2000-11-23 21:49:10
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/11/23 13:49:10 Modified files: gst : gstelement.c gstelement.h Log message: Closed 22145 - gstelement.c: support hotswapping of loopfunc Added a flag GST_ELEMENT_NEW_LOOPFUNC that's set when a new loopfunc is set, which needs to be obeyed by the loopfuncs themselves. The assumption is that only a loopfunc or an element that knows what it's doing will ever change the loopfunc pointer, so they can be responsible for exitting the loopfunc itself appropriately. The loopfunc_wrapper function has been changed to call the loopfunc pointer itself in a loop. If the loopfunc changes, the current loop is supposed to exit, which causes the loopfunc_wrapper to start up the new loopfunc. |
From: Erik W. <ome...@us...> - 2000-11-24 22:28:20
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/11/24 14:28:20 Modified files: gst : gstelement.c Log message: Fixed a dumb mistake: in gst_element_set_loop_function, it was forcing the cothread's entry function to change. This is totally wrong, the create_plan function in GstBin is responsible for setting that to its own internal helper function. Code removed outright... |
From: Erik W. <ome...@us...> - 2000-11-25 07:02:56
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/11/24 23:02:56 Modified files: gst : gstpad.c gstpad.h Log message: added the ability to disable pads, not quite complete but sufficient for now |
From: Erik W. <ome...@us...> - 2000-11-25 07:43:58
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/11/24 23:43:57 Modified files: gst/elements : gstelements.c Log message: Added code to force the gsttypes plugin to load before gstelements, by simply having gstelements.c request the plugin. Solves some dependency problems. This is the correct method of doing this for now, though I had a thought: Have a static list of hard dependencies that the plugin system is responsible for satisfying before even trying to load the plugin. Makes plugin design easier. |
From: Erik W. <ome...@us...> - 2000-11-29 10:05:49
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/11/29 02:05:48 Modified files: gst : cothreads.c Log message: Rearranged cothread_switch a bit to move all the code for error conditions to the end, using goto's to get there. This has the presumed advantage of consolidating all the normally run code into one chunk, reducing jumps (and the associated penalties in any modern processor) and limiting cache- line usage. It may be instructive to look at the generated assembly for this revision and the previous, to see if gcc is smart enough to do this for us anyway. If you want to turn off some of the checks (they are all checks for NULL pointers, if you're curious) for a speed gain, disable the #define of COTHREAD_PARANOID at the top. |
From: Erik W. <om...@cs...> - 2000-11-29 10:31:19
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On Wed, 29 Nov 2000, Erik Walthinsen wrote: > line usage. It may be instructive to look at the generated assembly for > this revision and the previous, to see if gcc is smart enough to do this > for us anyway. Wow. That *was* instructive: pushl %ebp cothread_switch (cothread_state *thread) { movl %esp,%ebp subl $12,%esp cmpl $0,8(%ebp) if (thread == NULL) jne .L24 jmp .L25 goto nothread; .p2align 4,,7 .L24: movl 8(%ebp),%eax movl (%eax),%edx movl %edx,-4(%ebp) ctx = thread->ctx; cmpl $0,-4(%ebp) if (ctx == NULL) jne .L26 jmp .L27 goto nocontext; .p2align 4,,7 .L26: . . . Man, that's *pathetic*! Then I realized that it was compiled with no optimization flags. Add -O6: pushl %ebp cothread_switch (cothread_state *thread) { movl %esp,%ebp subl $4,%esp pushl %esi pushl %ebx cmpl $0,8(%ebp) if (thread == NULL) je .L79 goto nothread; movl 8(%ebp),%ecx movl (%ecx),%ecx ctx = thread->ctx; movl %ecx,-4(%ebp) testl %ecx,%ecx if (ctx == NULL) je .L81 goto nocontext; . . . That's *much* better. Though it is interesting how those two tests are implemented differently, one with a direct compare to zero, the other by comparing against itself (I think, I'm not up on bare x86 asm). My guess is that it has something to do with alignment, since the cmpl requires as many as 5 or 6 bytes to the testl's 1 or 2, since the cmpl has to encode the $0 with as many as 32 bits. That restores my faith in gcc. And now to compare with the previous revision, where all the error handling is inline with the main code. I won't even bother trying without -O6: pushl %ebp cothread_switch (cothread_state *thread) { movl %esp,%ebp subl $4,%esp pushl %esi pushl %ebx cmpl $0,8(%ebp) if (thread == NULL) { jne .L78 pushl $.LC8 call g_print g_print("cothread: there's no thread... jmp .L77 return; } .p2align 4,,7 .L78: movl 8(%ebp),%ecx movl (%ecx),%ecx movl %ecx,-4(%ebp) ctx = thread->ctx movl 68(%ecx),%esi leal 0(,%esi,4),%eax movl (%eax,%ecx),%edx current = ctx->threads[ctx->current]; testl %edx,%edx if (current = NULL) { jne .L79 pushl $.LC9 call g_print g_print("cothread: there's no current... pushl $2 call exit exit(2); } .p2align 4,,7 .L79: . . . So, I was right. Moving the error handling to the end causes a noticable improvement in the quality of the generated asm, even with mega optimizations turned on. This does say that we really shouldn't even bother compiling without optimizations. I'll see if I can get that fixed. Erik Walthinsen <om...@cs...> - Staff Programmer @ OGI Quasar project - http://www.cse.ogi.edu/DISC/projects/quasar/ Video4Linux Two drivers and stuff - http://www.cse.ogi.edu/~omega/v4l2/ __ / \ SEUL: Simple End-User Linux - http://www.seul.org/ | | M E G A Helping Linux become THE choice _\ /_ for the home or office user |
From: Erik W. <ome...@us...> - 2000-12-02 10:07:51
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/02 02:07:50 Added files: docs/random : filter-writers-guide Log message: First pass at an outline for the Filter Writer's Guide. Mostly complete, though the structure needs some work. Just need someone to write it ;-) |
From: Erik W. <ome...@us...> - 2000-12-03 00:17:54
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/02 16:17:52 Modified files: gst : cothreads.c cothreads.h gst.h Log message: Enhanced debugging by making DEBUG() print out the cothread ID as well as the process ID. cothread_getcurrent returns the current cothread ID, or -1 if cothreads aren't set up in this process context. |
From: Erik W. <ome...@us...> - 2000-12-04 09:14:30
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/04 01:14:29 Modified files: plugins/mp3decode/parse: mp3parse.c Log message: Minor change to the head_check function: DEBUG pretty much assumes there's a newline (\n) at the end, things get messy otherwise. Might add a DEBUG_NOPREFIX to deal with this problem later, but I think this is a good cleanup anyway. |
From: Erik W. <ome...@us...> - 2000-12-04 09:32:45
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/04 01:32:43 Modified files: gst : gstplugin.c Log message: Added a check to see if the plugin actually exists before even bothering to try to load it. Saves a fair amount of debugging spew with _gst_plugin_spew enabled. |
From: Erik W. <ome...@us...> - 2000-12-04 09:35:09
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/04 01:35:08 Modified files: . : acconfig.h configure.in gst : Makefile.am gst.h gstbuffer.c cothreads.c Added files: gst : gstdebug.h Log message: Changes made to the DEBUG system. New header file gstdebug.h holds the stuff to keep it out of gst.h's hair. DEBUG prints out the process id, cothread id, source filename and line number. Two new macros DEBUG_ENTER and DEBUG_LEAVE are used to show the entry and exit of a given function. This eventually might be used to construct call trace graphs, even taking cothreads into account. This would be quite useful in visualizing the scheduling mechanism. Minor changes to various debug messages. Also sitting in gstdebug.h is a prototypical DEBUG_ENTER that's capable of performing DEBUG_LEAVE automatically. It does this by utilizing a little-known GCC extension that allows one to call a function with the same parameters as the current function. The macro uses this to basically call itself. A boolean is used to ensure that when it calls itself it actually runs the body of the function. In the meantime it prints stuff out before and after the real function, as well as constructing a debugging string. This can be used eventually to provide call-wide data on the DEBUG lines, instead of having to replicate data on each call to DEBUG. More research is needed into how this would most cleanly be fit into some other chunk of code, like GStreamer (I think of this DEBUG trick as a separate project, sorta). Unfortunately, the aforementioned DEBUG trick interacts quite poorly with cothreads. Almost any time it's used in a function that has anything remotely to do with a cothread context (as in, it runs in one), a segfault results from the __builtin_apply call, which is the heart of the whole thing. If someone who really knows assembly could analyze the resulting code to see what's really going on, we might find a way to fix either the macro or the cothreads (I'm thinking that there's something we missed in constructing the cothreads themselves) so this works in all cases. In the meantime, please insert both DEBUG_ENTER and DEBUG_LEAVE in your functions. Be sure to put DEBUG_ENTER after your variable declarations and before any functional code, not to put the function name in any DEBUG strings (it's already there, trust me), and put a DEBUG_LEAVE if you care enough. Changes are going to happen in the way DEBUGs and other printouts occur, so stay tuned. |
From: Erik W. <ome...@us...> - 2000-12-04 10:52:31
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/04 02:52:30 Modified files: gst : gstbin.c gstelement.h gstpad.c gstpad.h gstpipeline.c gstsrc.c gstsrc.h gst/elements : gstasyncdisksrc.c gstaudiosrc.c gstdisksrc.c gstfakesrc.c gstfdsrc.c gsthttpsrc.c gstsinesrc.c Log message: Changed the way things are scheduled, especially sources. A Src used to have a push() function, and optionally a pushregion() to deal with async reads, etc. That whole thing has gone away, in favor of providing a pull() function for the output (Src) pad instead, ala chain functions. This makes constructing cothreaded schedules out of non-loop elements somewhat easier. Basically there was always a question as to which pad was being dealt with. In the pullregion case, cothread-specific data was used to try to pass the region struct to the right place, which is a slow hack. And in general, the push function severely limited the kind of tricks that could be played when there's more than one output pad, such as a multi-out file reader with async capabilities on each pad independently. This changes the way cothread scheduling occurs. Instead of the hack to deal with Src's by calling their push() function (or optionally the pushregion(), in certain cases), we now are working towards a general mechanism where pads are the only thing that are dealt with directly. An optimization was made in the process of doing this: the loopfunction actually run as the outer [stack] frame of the cothread is now set more intelligently in create_plan() based on what kind of element it is. We now have: loopfunc_wrapper: used for loop-based elements, it simply calls the loopfunc in a loop, paying attention to COTHREAD_STOPPING (see below). It currently does other, soon to be depracated, stuff. pullsrc_wrapper: wraps a Src that's not loop-based (since your options are now loop- or pull-based) There will be a couple more to deal with other cases, such as Connections and chain-based elements. The general idea is that it's a lot more efficient to make the decisions once in create_plan than to keep doing this huge if/else chain in the wrapper. Just choose the right wrapper up front. It'll be most apparent performance-wise in the case of whichever element context is switched to first for each iteration, since the whole wrapper setup is done for every iteration. The tricky part is that there is now a bit of overloading of the function pointers in a pad. The current meanings (possibly to change a bit more soon) are: chainfunc: as always, chainfunc pointer is mirrored between peer pads (this may change, and the chain func may end up in pushfunc) pushfunc: SrcPad: gst_pad_pushfunc_proxy, cothread_switch to peer SinkPad: none (may take over chainfunc, see below) pullfunc: SrcPad: Src or Connection's function to construct buffers SinkPad: gst_pad_pullfunc_proxy, cothread_switch to peer There are a number of issues remaining with the scheduling, not the least of which is the fact that Connections are still dealt with the old way, with _push() functions and such. I'm trying to figure out a way to unify the system so it makes sense. Following the scheduling system is hard enough, trying to change it is murder. Another useful scheduling addition, mentioned above, is COTHREAD_STOPPING. It's an element flag that's used to signal whatever code is running in cothread context that it should be finishing up and exiting soon. An example of this is in plugins/cobin/spindentity.c. All the loops should now be composed of do/while loops, rather than while(1) loops: do { buf = gst_pad_pull(spindentity->sinkpad); gst_pad_push(spindentity->srcpad,buf); } while (!GST_ELEMENT_IS_COTHREAD_STOPPING(element)); The reason for this is that COTHREAD_STOPPING may be set before the above loop ever gets started. It wouldn't do for the body of the loop to never once get called, that would simply stall the pipeline. Note that only the core library code is ever responsible for setting and unsetting this flag. All elements have to do is respond to it by cleanly exiting the loop and the function holding it. This is needed primarily to allow iterations to occur properly. Basically, there's a single entry point in the cothread scheduling loop, gst_bin_iterate_func() simply switches to this cothread. If the element in this context is allowed to loop infinitely, nothing would even switch back to the context from which the iterate() was originally called. This is a bit of a problem. The solution is for there to be an implicit switch back to the originating context. Now, even I'm not sure exactly how this works, but if the cothread that's switched to actually returns, execution returns back to the calling context, i.e. iterate_func(). COTHREAD_STOPPING is therefore set just before switching into this (currently randomly chosen) context, on the assumption that it will return promptly after finishing its duties. The burden of clearing the flag falls to the various wrapper functions provided by the Bin code, thus element writers don't have to worry about doing that at all (and simply shouldn't). Related changes: All the sources in elements/ have been changed to reflect the new system. FIXMEs: 1) gstpipeline.c calls gst_src_push at some point, dunno why, it's commented out now. 2) any other sources, including vcdsrc, dvdsrc, and v4lsrc will break badly and need to be modified to work as pull-based sources. |
From: Erik W. <ome...@us...> - 2000-12-08 10:33:02
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/08 02:33:01 Modified files: gst : gstbin.c gstconnection.c gstconnection.h gstdebug.h gstelement.c gstpad.c gst/elements : gstqueue.c Log message: Another big set of changes. Connections are now also pullfunc based. gstqueue has been updated, I don't know of any other connections offhand. There are still a few things that need doing, specifically the concept of a source or connection with connections to multiple thread contexts is not dealt with. This may force us to move the threadstate from the element to the pad, maybe keeping the element's copy for simple cases. Then the Bin would create a structure to pass to the cothreaded _wrappers of any such elements, which would detail the pads that are to be dealt with by this particular cothread context. That will speed things up to, since we don't have to look through the list of all pads for every Src or Connection element for every iteration, we can simply step through the list provided by the plan. Special case might even have a single pad pointer sitting there to trump the list, if there's only one (the common case anyway). Task 23098 is tracking these changes. The main task 22588 depends on that subtask, as well as 22240, which is a consistency check on PAD_DISABLED. |
From: Erik W. <ome...@us...> - 2000-12-08 20:31:41
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/08 12:31:41 Modified files: tests : Makefile.am Added files: tests : queue.c Log message: Test program for simple queue operations. Good for testing thread/cothread interations. |
From: Erik W. <ome...@us...> - 2000-12-08 23:38:16
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/08 15:38:12 Modified files: gst : gstbin.c gstthread.c Log message: Mostly debugging changes. What's in CVS seems to work rather well, actually. Next is the work on task 23098... |
From: Erik W. <ome...@us...> - 2000-12-09 09:13:10
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/09 01:13:09 Modified files: gst : gstbin.c gstbin.h gstelement.c gstpad.h Log message: Snapshot of work-in-progress do deal with out-of-bin elements. Current system is very likely going to be ditched due to its complexity and the fact that it doesn't work right now. More than that, it's generating some really odd results in my test program, which aren't readily explainable. If you want to keep a working copy of your working copy (heh), don't update until this is replaced with a hybrid approach. This approach will be the beginning of a plan generator that can construct full hybrid schedules given hints from various places. Hybrid means that cothreads are used, but there are chunks of the pipeline that are actually dealt with by chaining. This can improve speed by reducing cothread switches (which are much cheaper than thread switches, but still far from free, about 570 cycles on my PIII), but does carry a complexity burden. Luckily, the structure of GStreamer allows that burden to live entirely in create_plan. Luck? I think not ;-) |
From: Erik W. <ome...@us...> - 2000-12-11 00:24:32
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/10 16:24:32 Modified files: gst : gstbin.c gstdebug.h gstelement.c gstpad.c gst/elements : gstqueue.c Log message: Implemented the hybrid scheduling system for sources and connections outside the current Bin. Is a bit hackish in one place, but I'll work out a way to make that cleaner soon. queue.c in tests now works nicely in all cases. More to come later. |
From: Erik W. <ome...@us...> - 2000-12-11 00:25:06
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/10 16:25:06 Modified files: tests : queue.c Log message: Updated to latest code for testing scheduling. |
From: Erik W. <ome...@us...> - 2000-12-12 06:43:11
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/11 22:43:11 gstreamer/plugins/cdparanoia Update of /cvsroot/gstreamer/gstreamer/plugins/cdparanoia In directory slayer.i.sourceforge.net:/tmp/cvs-serv4793/cdparanoia Log Message: Directory /cvsroot/gstreamer/gstreamer/plugins/cdparanoia added to the repository |
From: Erik W. <ome...@us...> - 2000-12-12 06:49:27
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/11 22:49:26 Modified files: . : configure.in plugins : Makefile.am tests : Makefile.am editor : gstelementselect.c Added files: tests : paranoia.c plugins/cdparanoia: Makefile.am cdparanoia.c cdparanoia.h Log message: Brand new source, the cdparanoia source. Reads audio data from a CD, writes out raw audio. The tests/paranoia.c program will simply hook this up to a sound card. It works perfectly. Next step is to flesh out the rest of the element, including pad caps, better seek and playout control, signals, and whatever else comes up. A minor patch to the editor is included here, the GstElementFactory details struct has a name change from 'class' to 'klass' that wasn't reflected in the elementselect widget. Fixd. |
From: Erik W. <ome...@us...> - 2000-12-12 07:33:42
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/11 23:33:41 gstreamer/plugins/mp3encode Update of /cvsroot/gstreamer/gstreamer/plugins/mp3encode In directory slayer.i.sourceforge.net:/tmp/cvs-serv8538/mp3encode Log Message: Directory /cvsroot/gstreamer/gstreamer/plugins/mp3encode added to the repository |
From: Erik W. <ome...@us...> - 2000-12-12 07:33:52
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CVSROOT: /cvsroot/gstreamer Module name: gstreamer Changes by: omegahacker 00/12/11 23:33:52 gstreamer/plugins/mp3encode/lame Update of /cvsroot/gstreamer/gstreamer/plugins/mp3encode/lame In directory slayer.i.sourceforge.net:/tmp/cvs-serv8555/lame Log Message: Directory /cvsroot/gstreamer/gstreamer/plugins/mp3encode/lame added to the repository |