Messages in this thread |  | | Date | Thu, 30 Nov 2000 10:43:01 +0100 | From | uaca@alumni ... |
| |
In a 2.4 kernel, mm/page_alloc.c:free_area_init_core(), in the following assignement...
bitmap_size = size >> i;
...makes bitmap_size be the double of the needed size, this calculum assumes that with a 512 byte map size the kernel is mapping 8*512= 4096 chunks of memory, that is: one bit of the map is used for each chunk of memory, and that's not true.
Really one bit of area->map is used to map two chunks of memory, so in the example above an area->map of just 256 bytes is really needed, the other 256 bytes are _never accessed_.
So the righ thing would be to do is:
bitmap_size = size >> (i+1);
also I tested it and it works ok, so I believe I'm right...
Please CC: your replies to (I'm not subscribed to this list)
Ulisses Alonso Camaró <uaca@NOSPAM.alumni.uv.es>
PD: my nick on #kernelnewbies is despistao
Debian GNU/Linux: a dream come true ----------------------------------------------------------------------------- "Computers are useless. They can only give answers." Pablo Picasso
---> Visita http://www.valux.org/ para saber acerca de la <--- ---> Asociación Valenciana de Usuarios de Linux <--- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
|  |