Messages in this thread | | | From | tabris <> | Subject | Re: [LKML]kmalloc -contiguous locations ? | Date | Mon, 31 May 2004 19:24:00 -0400 |
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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)
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