[fpc-devel]How to subscribe to list
Michael Van Canneyt
michael.vancanneyt at wisa.be
Mon Nov 6 09:34:09 CET 2000
On Mon, 6 Nov 2000, Sergey Korshunoff wrote:
> Hello everybody.
> There is no description in FPC doc's about this list subscription.
> May be it is better to put some doc's about this procedure in FPC
> doc's insteed of following sentense in readme.txt:
> Information about available lists and subscription can be found
> on http://lists.freepascal.org/mailman/listinfo
> I do not have direct internet access. Can You send me answer by
> Sergey Korshunoff
> PS: I have modified version of heap manager for FPC (v1.00).
> In FPC 1.02 problem of memory fragmentation was solved in "FreeMem"
> procedure. I think this is not so good. In my version a merging
> is performed in "GetMem" procedure (when we looking freelists
> for a free memory block).
> This is faster (about 20% faster for a GetMem/FreeMem test cycle)
> And my version do not allocate new memory from system if
> we have continius memory block of needed size (in v1.02 we do not
> merge blocks which start from some block in freelists[1..x])
> Well. There is notes about my changes (related to v1.00):
> Sergey Korshunoff (seyko at p5.f434.n5020.z2.fidonet.org):
> 1. Some constants moved from heaph.inc to this file.
> 2. Value returned by `SysMaxavail' is more correct now.
> 3. In SysGetMem:
> is moved near to succesful exit (or we need to decrement
> internal_memavail when we fail to allocate memory).
> 4. Handle case when `HeapError' return value is not in [0,1,2].
> 5. Now we repeat a full memory search path when `HeapError' say
> to try again. This is like Borland `GetMem' do it. And
> this allow us to handle a case when `HeapError' lead to
> a `FreeMem' call without adding any new memory from OS.
> 6. BESTMATCH removed (it is time consuming procedure)
> 7. SysGetMem now merges blocks.
> 8. `heaporg', `heapptr' and `beforeheapendmask' are
> not used now and removed (new memory from system go directly
> to free list)
I don't know what the effect is of the above 8 points;
this should be looked at by Peter Vreman or Pierre Muller.
> 9. Procedure ReAllocMem in TMemoryManager record now takes
> 3rd paramater: a size of memory in old block which
> contain information (some time it is much faster do not
> to copy not used data from the old block)
AFAIK, this is not Delphi compatible; it should be removed again.
> 10. Functions 'SysGetMem, Sys..' are removed from heaph.inc
> because you should use MemoryManager for this job.
Not good, since someone may wish to install a memory manager that does
not override all functions, so they may wish to have access to the
> I replaced a call to syscall_nr_mmap by a call to syscall_nr_brk:
> 1) with syscall_nr_mmap first block of memory, reserved by FPC option
> "-Cs<n> set stack size to <n>",
> and second memory block, asked from Linux, will never be merged.
> 2) Linux do not allow restrict amount of memory (used by
> program) if this memory is not allocated by syscall_nr_brk.
This is not good; the linux memory system used to use syscall_nr_brk,
this was changed to syscall_nr_mmap() to be compatible with C libraries.
C libraries use mmap(); if we use brk() then this creates conflicts.
> cmem.pp from source/packages:
> CHeapSize and CMemAvail was added. CMEM do not return memory
> to system now (this behavior is like behavior of standard heap package).
> now CMEM really do a work (there was some errors: before changes
> adding CMEM in Uses statements lead to not working program).
Corrections to cmem may be sent to me; please send a context diff file.
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