>>>>> "WK" == WK Yeung <kit@kitkit.net> writes:
WK> Yes, I agree. According to my memory, Linux's swap should not more
WK> than 128MB or it is wasted, it is limited by some constrains I can't
WK> remember, try to search for it in newsgroup.
I no longer hold: from the man page of mkswap(8):
Linux knows about two styles of swap areas, old style and
new style. The last 10 bytes of the first page of the
swap area distinguishes them: old style has `SWAP_SPACE',
new style has `SWAPSPACE2' as signature.
In the old style, the rest of this first page was a bit
map, with a 1 bit for each usable page of the swap area.
Since the first page holds this bit map, the first bit is
0. Also, the last 10 bytes hold the signature. So, if the
page size is S, an old style swap area can describe at
most 8*(S-10)-1 pages used for swapping. With S=4096 (as
on i386), the useful area is at most 133890048 bytes
(almost 128 MiB), and the rest is wasted. On an alpha and
sparc64, with S=8192, the useful area is at most 535560992
bytes (almost 512 MiB).
The old setup wastes most of this bitmap page, because
zero bits denote bad blocks or blocks past the end of the
swap space, and a simple integer suffices to indicate the
size of the swap space, while the bad blocks, if any, can
simply be listed. Nobody wants to use a swap space with
hundreds of bad blocks. (I would not even use a swap space
with 1 bad block.) In the new style swap area this is
precisely what is done. The maximum useful size of a swap
area now depends on the architecture. It is roughly 2GiB
on i386, PPC, m68k, ARM, 1GiB on sparc, 512MiB on mips,
128GiB on alpha and 3TiB on sparc64.
Regards,
Isaac.
--
| This message was re-posted from debian-chinese-big5@lists.debian.org
| and converted from big5 to gb2312 by an automatic gateway.Attachment:
pgp0AQ3Bd3LUz.pgp
Description: PGP signature