* Re: [LKML]kmalloc -contiguous locations ?
2004-05-31 9:49 [LKML]kmalloc -contiguous locations ? Shobhit Mathur
@ 2004-05-31 23:24 ` tabris
0 siblings, 0 replies; 2+ messages in thread
From: tabris @ 2004-05-31 23:24 UTC (permalink / raw)
To: Shobhit Mathur; +Cc: linux-kernel
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On Monday 31 May 2004 5:49 am, Shobhit Mathur wrote:
> Hello,
>
> I would like to know whether kmalloc() guarantees
> virtually contiguous memory locations ?
> Is there a limit on the amount of contiguous memory
> that can be returned by kmalloc() ?
First, kmalloc returns physically contiguous memory.
second, the limit (on x86) is 128kb (32 pages), allocatable in powers of two
pages. (1,2,4,8,16,32. often called 0-order thru 5-order allocations)
vmalloc returns virtual contiguous allocations, with no guarantee on physical
contiguity. The problem with vmalloc, iirc, is that there's a [total] limit
of 128MB for vmallocs.
Also remember that all kernel memory allocated with vmalloc() or kmalloc() is
non-swappable.
I don't know how this changes under any other architecture, such as x86-64 or
PPC32/64.
>
> - Thank you
>
> - Shobhit Mathur
- --
tabris
- -
A master was explaining the nature of Tao to one of his novices.
"The Tao is embodied in all software -- regardless of how insignificant,"
said the master.
"Is Tao in a hand-held calculator?" asked the novice.
"It is," came the reply.
"Is the Tao in a video game?" continued the novice.
"It is even in a video game," said the master.
"And is the Tao in the DOS for a personal computer?"
The master coughed and shifted his position slightly. "The lesson
is over for today," he said.
-- Geoffrey James, "The Tao of Programming"
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (GNU/Linux)
iD8DBQFAu76V1U5ZaPMbKQcRAh8MAJ4nXgcFr/AENZql4BDFIRL+HGGJzACeNqej
TPVXSEF6E0ud+MfA8g5tQqE=
=sgpU
-----END PGP SIGNATURE-----
^ permalink raw reply [flat|nested] 2+ messages in thread