Messages in this thread | | | Subject | Re: [PATCH,preliminary] cleanup shm handling | From | Christoph Rohland <> | Date | 08 Dec 2000 23:21:57 +0100 |
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Hi Linus,
Linus Torvalds <torvalds@transmeta.com> writes: > On 8 Dec 2000, Christoph Rohland wrote: > > > > here is my first shot for cleaning up the shm handling. It did > > survive some basic testing but is not ready for inclusion. > > The only comment I have right now is that you probably should not > mark the page dirty in "nopage" - theoretically somebody might have > a sparse mapping and depend on zero pages for the ones that aren't > touched. It's better to delay the dirty marking until swapout() (and > write(), when that is implemented), so that we don't needlessly > create swap entries for zero pages.
OK. I simply copied that from shm.c without thinking. Actually I do not yet understand the implications of it. (I never thought that I would get so deeply involved into these issues and still struggle often with the details)
> Other than that the approach at least looks reasonable. And cleaner > than what we currently have.
Only reasonable? :-(
It's what I always thought would be the Right Thing (TM):
1) The mm layer should have the abilty to handle shared anonymous pages 2) To access this we should use the 'everything is a file' mantra which means shm fs 3) sysv shm should only care about handling shm ids (and it special attributes which unfortunately makes shm_vm_operations necessary.)
So how would you improve it conceptually? And where are the implementation flaws?
And compared to all the ipc/shm.c hacks we had so far it looks for me beautiful. (And to make this clear: The main part is not my work. I simply gathered the work of others to make this possible)
Christoph
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