Malloc impl

Implements Malloc.

Summary

Malloc impl	Implements Malloc.
Copyright	This program is free software.
Files
C-kern/api/platform/malloc.h	Header file of Malloc.
C-kern/platform/Linux/malloc.c	Implementation file of Malloc impl.
malloc
static variables
s_isprepared_malloc	Remembers if prepare_malloc was called already.
init
prepare_malloc	Calls functions to force allocating of system memory.
manage
trimmemory_malloc	Uses GNU malloc_trim extension.
query
allocatedsize_malloc impl	Uses GNU malloc_stats extension.
test

Copyright

This program is free software. You can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Author

Files

C-kern/api/platform/malloc.h

Header file of Malloc.

C-kern/platform/Linux/malloc.c

Implementation file of Malloc impl.

malloc

Summary

static variables
s_isprepared_malloc	Remembers if prepare_malloc was called already.
init
prepare_malloc	Calls functions to force allocating of system memory.
manage
trimmemory_malloc	Uses GNU malloc_trim extension.
query
allocatedsize_malloc impl	Uses GNU malloc_stats extension.
test

static variables

s_isprepared_malloc

static bool s_isprepared_malloc

Remembers if prepare_malloc was called already.

init

prepare_malloc

int prepare_malloc()

Calls functions to force allocating of system memory. No own malloc version is initialized: See allocatedsize_malloc for why.

manage

trimmemory_malloc

int trimmemory_malloc()

Uses GNU malloc_trim extension. This function may be missing on some platforms. Currently it is only working on Linux platforms.

query

allocatedsize_malloc impl

Uses GNU malloc_stats extension. This functions returns internal collected statistics about memory usage so implementing a thin wrapper for malloc is not necessary. This function may be missing on some platforms. Currently it is only tested on Linux platforms.

What malloc_stats does

The GNU C lib function malloc_stats writes textual information to standard err in the following form:

Arena 0:
system bytes     =     135168
in use bytes     =      15000
Total (incl. mmap):
system bytes     =     135168
in use bytes     =      15000
max mmap regions =          0
max mmap bytes   =          0

How it is implemented

This function redirects standard error file descriptor to a pipe and reads the content of the pipe into a buffer. It scans backwards until the third last line is reached (“in use bytes”) and then returns the converted the number at the end of the line as result.