Messages in this thread | | | Date | Mon, 26 Mar 2007 17:02:10 -0700 | From | William Lee Irwin III <> | Subject | Re: [patch 2/3] only allow nonlinear vmas for ram backed filesystems |
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On Sat, 2007-03-24 at 23:09 +0100, Miklos Szeredi wrote: >>> Dirty page accounting/limiting doesn't work for nonlinear mappings, so >>> for non-ram backed filesystems emulate with linear mappings. This >>> retains ABI compatibility with previous kernels at minimal code cost. >>> All known users of nonlinear mappings actually use tmpfs, so this >>> shouldn't have any negative effect.
On Sun, Mar 25, 2007 at 02:12:32PM +0200, Peter Zijlstra wrote:
On Sun, Mar 25, 2007 at 10:51:27AM -0500, Matt Mackall wrote: > They do? I thought the whole point of nonlinear mappings was for > mapping files bigger than the address space (eg. databases). Is Oracle > instead using this to map >3G files on a tmpfs??
It's used for > 3GB files on tmpfs and also ramfs, sometimes substantially larger than 3GB.
It's not used for the database proper. It's used for the buffer pool, which is the in-core destination and source of direct I/O, the on-disk source and destination of the I/O being the database.
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