diff options
| -rw-r--r-- | include/malloc.h | 9 | ||||
| -rw-r--r-- | libc/stdlib/malloc-standard/free.c | 31 | ||||
| -rw-r--r-- | libc/stdlib/malloc-standard/mallinfo.c | 25 |
3 files changed, 65 insertions, 0 deletions
diff --git a/include/malloc.h b/include/malloc.h index 790390db7..610c47dc3 100644 --- a/include/malloc.h +++ b/include/malloc.h @@ -145,6 +145,15 @@ struct mallinfo { /* Returns a copy of the updated current mallinfo. */ extern struct mallinfo mallinfo __MALLOC_P ((void)); +/* Release all but __pad bytes of freed top-most memory back to the + system. Return 1 if successful, else 0. */ +extern int malloc_trim(size_t pad); + +#include <stdio.h> +/* Prints brief summary statistics to the specified file. + * Writes to stderr if file is NULL. */ +extern void malloc_stats(FILE *file); + /* SVID2/XPG mallopt options */ #ifndef M_MXFAST # define M_MXFAST 1 /* UNUSED in this malloc */ diff --git a/libc/stdlib/malloc-standard/free.c b/libc/stdlib/malloc-standard/free.c index 4277767fa..ec4debd56 100644 --- a/libc/stdlib/malloc-standard/free.c +++ b/libc/stdlib/malloc-standard/free.c @@ -17,6 +17,37 @@ #include "malloc.h" +/* ------------------------- malloc_trim ------------------------- + malloc_trim(size_t pad); + + If possible, gives memory back to the system (via negative + arguments to sbrk) if there is unused memory at the `high' end of + the malloc pool. You can call this after freeing large blocks of + memory to potentially reduce the system-level memory requirements + of a program. However, it cannot guarantee to reduce memory. Under + some allocation patterns, some large free blocks of memory will be + locked between two used chunks, so they cannot be given back to + the system. + + The `pad' argument to malloc_trim represents the amount of free + trailing space to leave untrimmed. If this argument is zero, + only the minimum amount of memory to maintain internal data + structures will be left (one page or less). Non-zero arguments + can be supplied to maintain enough trailing space to service + future expected allocations without having to re-obtain memory + from the system. + + Malloc_trim returns 1 if it actually released any memory, else 0. + On systems that do not support "negative sbrks", it will always + return 0. +*/ +int malloc_trim(size_t pad) +{ + mstate av = get_malloc_state(); + __malloc_consolidate(av); + return __malloc_trim(pad, av); +} + /* ------------------------- __malloc_trim ------------------------- __malloc_trim is an inverse of sorts to __malloc_alloc. It gives memory back to the system (via negative arguments to sbrk) if there is unused diff --git a/libc/stdlib/malloc-standard/mallinfo.c b/libc/stdlib/malloc-standard/mallinfo.c index 89d6b68e1..f35aab00f 100644 --- a/libc/stdlib/malloc-standard/mallinfo.c +++ b/libc/stdlib/malloc-standard/mallinfo.c @@ -79,3 +79,28 @@ struct mallinfo mallinfo(void) return mi; } +void malloc_stats(FILE *file) +{ + struct mallinfo mi; + + if (file==NULL) { + file = stderr; + } + + mi = mallinfo(); + fprintf(file, "total bytes allocated = %10lu\n", (unsigned int)(mi.arena + mi.hblkhd)); + fprintf(file, "total bytes in use bytes = %10lu\n", (unsigned int)(mi.uordblks + mi.hblkhd)); + fprintf(file, "total non-mmapped bytes allocated = %10lu\n", (unsigned int)(mi.arena)); + fprintf(file, "number of mmapped regions = %10lu\n", (unsigned int)(mi.hblks)); + fprintf(file, "total allocated mmap space = %10lu\n", (unsigned int)(mi.hblkhd)); + fprintf(file, "total allocated sbrk space = %10lu\n", (unsigned int)(mi.uordblks)); +#if 0 + fprintf(file, "number of free chunks = %10lu\n", (unsigned int)(mi.ordblks)); + fprintf(file, "number of fastbin blocks = %10lu\n", (unsigned int)(mi.smblks)); + fprintf(file, "space in freed fastbin blocks = %10lu\n", (unsigned int)(mi.fsmblks)); +#endif + fprintf(file, "maximum total allocated space = %10lu\n", (unsigned int)(mi.usmblks)); + fprintf(file, "total free space = %10lu\n", (unsigned int)(mi.fordblks)); + fprintf(file, "memory releasable via malloc_trim = %10lu\n", (unsigned int)(mi.keepcost)); +} + |