Messages in this thread | | | Date | Wed, 25 Feb 2004 11:12:19 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [RFC] Distributed mmap API |
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On Wed, Feb 25, 2004 at 04:04:19PM -0500, Daniel Phillips wrote:
Very cool!
> This is the function formerly known as invalidate_mmap_range, with the > addition of a new code path in the zap_ call chain to handle MAP_PRIVATE > properly. This function by itself is enough to support a crude but useful > form of distributed mmap where a shared file is cached only on one cluster > node at a time. > > To use this, the distributed filesystem has to hook do_no_page to intercept > page faults and carry out the needed global locking. The locking itself does > not require any new kernel hooks. In brief, the patch here and another patch > to be presented for the do_no_page hook, together provide the core kernel API > for a simplified, distributed mmap. (Note that there may be a workaround for > the lack of a do_no_page hook, but certainly not as simple and robust.) > > To put this in perspective, I'll mention the two big limitations of the > simplified API: > > 1) Invalidation is always a whole file at a time
I must be missing something subtle here... It looks to me like the new unmap_mapping_range() API is capable of invalidating portions of files, based on the "start" and "length" arguments.
What am I missing?
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