diff options
Diffstat (limited to 'README')
| -rw-r--r-- | README | 50 |
1 files changed, 38 insertions, 12 deletions
@@ -11,7 +11,7 @@ Permission to modify the code and to distribute modified code is granted, provided the above notices are retained, and a notice that the code was modified is included with the above copyright notice. -This is version 4.14 of a conservative garbage collector for C and C++. +This is version 5.0alpha1 of a conservative garbage collector for C and C++. You might find a more recent version of this at @@ -23,7 +23,7 @@ HISTORY - projects supported in part by the National Science Foundation and the Defense Advance Research Projects Agency. Much of the code was rewritten by Hans-J. Boehm at Xerox PARC -and is now maintained by him at SGI (boehm@sgi.com). +and is now maintained by him at SGI (boehm@sgi.com or boehm@acm.org). Some other contributors: @@ -40,8 +40,8 @@ Robert Brazile (brazile@diamond.bbn.com) originally supplied the ULTRIX code. Al Dosser (dosser@src.dec.com) and Regis Cridlig (Regis.Cridlig@cl.cam.ac.uk) subsequently provided updates and information on variation between ULTRIX systems. Parag Patel (parag@netcom.com) supplied the A/UX code. -Jesper Peterson(jep@mtiame.mtia.oz.au) and -Michel Schinz supplied the Amiga port. +Jesper Peterson(jep@mtiame.mtia.oz.au), Michel Schinz, and +Martin Tauchmann (martintauchmann@bigfoot.com) supplied the Amiga port. Thomas Funke (thf@zelator.in-berlin.de(?)) and Brian D.Carlstrom (bdc@clark.lcs.mit.edu) supplied the NeXT ports. Douglas Steel (doug@wg.icl.co.uk) provided ICL DRS6000 code. @@ -612,7 +612,7 @@ reclaimed. Exclusive-or'ing forward and backward links in a list doesn't cut it. Some C optimizers may lose the last undisguised pointer to a memory object as a consequence of clever optimizations. This has almost -never been observed in practice. Send mail to boehm@sgi.com +never been observed in practice. Send mail to boehm@acm.org for suggestions on how to fix your compiler. This is not a real-time collector. In the standard configuration, percentage of time required for collection should be constant across @@ -621,7 +621,7 @@ heap sizes. But collection pauses will increase for larger heaps. per MB of accessible memory that needs to be scanned. Your mileage may vary.) The incremental/generational collection facility helps, but is portable only if "stubborn" allocation is used. - Please address bug reports to boehm@sgi.com. If you are + Please address bug reports to boehm@acm.org. If you are contemplating a major addition, you might also send mail to ask whether it's already been done (or whether we tried and discarded it). @@ -1452,6 +1452,37 @@ Since 4.14alpha1 Since 4.14alpha2 - changed STACKBOTTOM for DJGPP (Thanks to Salvador Eduardo Tropea). +Since 4.14 + - Reworked large block allocator. Now uses multiple doubly linked free + lists to approximate best fit. + - Changed heap expansion heuristic. Entirely free blocks are no longer + counted towards the heap size. This seems to have a major impact on + heap size stability; the old version could expand the heap way too + much in the presence of large block fragmentation. + - added -DGC_ASSERTIONS and some simple assertions inside the collector. + This is mainlyt for collector debugging. + - added -DUSE_MUNMAP to allow the heap to shrink. Suupported on only + a few UNIX-like platforms for now. + - added GC_dump_regions() for debugging of fragmentation issues. + - Changed PowerPC pointer alignment under Linux to 4. (This needs + checking by someone who has one. The suggestions came to me via a + rather circuitous path.) + - Changed the Linux/Alpha port to walk the data segment backwards until + it encounters a SIGSEGV. The old way to find the start of the data + segment broke with a recent release. + - cordxtra.c needed to call GC_REGISTER_FINALIZER instead of + GC_register_finalizer, so that it would continue to work with GC_DEBUG. + - allochblk sometimes cleared the wrong block for debugging purposes + when it dropped blacklisted blocks. This could result in spurious + error reports with GC_DEBUG. + - added MACOS X Server support. (Thanks to Andrew Stone.) + - Changed the Solaris threads code to ignore stack limits > 8 MB with + a warning. Empirically, it is not safe to access arbitrary pages + in such large stacks. And the dirty bit implementation does not + guarantee that none of them will be accessed. + - Integrated Martin Tauchmann's Amiga changes. + - Inetgrated James Dominy's OpenBSD/SPARC port. + To do: - Very large root set sizes (> 16 MB or so) could cause the collector to abort with an unexpected mark stack overflow. (Thanks again to @@ -1469,9 +1500,4 @@ To do: blocks reside in the newly allocated heap section, the heuristic for temporarily ignoring black-listing fails, and the heap grows too much. (This was observed in only one case, and could be worked around, but ...) - - I've started work on rewriting the large block allocator to use approximate - best fit. There are rare cases in which the current allocator results in - excessive large block fragmentation, even with the 4.13 fixes. This should - also reduce large block allocation time, whcih has become occasionally - noticable in 4.13. - + - Some platform specific updates are waiting for 4.15alpha1. |