Re: SMP/cc Cluster description

Larry McVoy (lm@bitmover.com)
Thu, 6 Dec 2001 14:32:18 -0800

On Thu, Dec 06, 2001 at 10:38:14PM +0000, Alan Cox wrote:
> > the hardware's coherency. No locks in the vfs or fs, that's all done
> > in the mmap/page fault path for sure, but once the data is mapped you
> > aren't dealing with the file system at all.
>
> ftruncate

I'm not sure what the point is. We've already agreed that the multiple OS
instances will have synchonization to do for file operations, ftruncate
being one of them.

I thought the question was how N user processes do locking and my answer
stands: exactly like they'd do it on an SMP, with mutex_enter()/exit() on
some portion of the mapped file. The mapped file is just a chunk of cache
coherent memory.

-- 

---
Larry McVoy            	 lm at bitmover.com           http://www.bitmover.com/lm 
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