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Re: Review of Thomas's >2GB ext2fs proposal
From: |
Thomas Bushnell BSG |
Subject: |
Re: Review of Thomas's >2GB ext2fs proposal |
Date: |
16 Aug 2004 11:06:32 -0700 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 |
So I think that this review is mostly accurate.
My real questions are:
1) Why muck with the well-understood memory object model?
2) Mach won't use more memory under my proposal; you have simply moved
around where the memory is. Instead of taking more memory to hold
a table of physical->virtual address mappings in the memory object,
you have a table of virtual->backing_store mappings in the pager;
but it is the same data and it has to be stored either way.
3) I REALLY REALLY prefer keeping the memory object interface clear;
experience is that this is a huge source of constant bugs. In
addition, adopting your strategy is way tougher to debug, because
it's a big kernel change, rather than a simple user-space one.
4) And finally, what about data caching--which is vastly more
important than mapping caching? My version has it that data is
cached as long as the kernel wants to keep it around, and in a
fashion decoupled from mappings.
But the moral of Neil's analysis is basically a good one: his proposal
and mine do the same tasks, but in different places. My proposal is
better because it does these tasks in user space.
Thomas
- Ognyan's libpager changes, Neal H. Walfield, 2004/08/02
- Re: Ognyan's libpager changes, Ognyan Kulev, 2004/08/02
- Review of Roland's >2GB ext2fs proposal, Neal H. Walfield, 2004/08/13
- Review of Thomas's >2GB ext2fs proposal, Neal H. Walfield, 2004/08/16
- Re: Review of Thomas's >2GB ext2fs proposal,
Thomas Bushnell BSG <=
- Re: Review of Thomas's >2GB ext2fs proposal, Neal H. Walfield, 2004/08/16
- Re: Review of Thomas's >2GB ext2fs proposal, Thomas Bushnell BSG, 2004/08/16
- Re: Review of Thomas's >2GB ext2fs proposal, Neal H. Walfield, 2004/08/17
- Re: Review of Thomas's >2GB ext2fs proposal, Thomas Bushnell BSG, 2004/08/17
- Re: Review of Thomas's >2GB ext2fs proposal, Neal H. Walfield, 2004/08/17
- Re: Review of Thomas's >2GB ext2fs proposal, Thomas Bushnell BSG, 2004/08/17
- Re: Review of Thomas's >2GB ext2fs proposal, Ognyan Kulev, 2004/08/17
- Re: Review of Thomas's >2GB ext2fs proposal, Thomas Bushnell BSG, 2004/08/17
- Re: Review of Thomas's >2GB ext2fs proposal, Neal H. Walfield, 2004/08/17
- Re: Review of Thomas's >2GB ext2fs proposal, Ognyan Kulev, 2004/08/17