Is there still a chance that the skas0 patch will end up in the mainline?
> On Tue, Dec 06, 2011 at 07:48:40PM +0100, Riccardo Murri wrote: >> Sorry again for resurrecting an old thread, but I each time I look >> into this issue I realize that I haven't quite understood the details... > > You basically have it all right. > >> In addition, *every* syscall generates a SIGTRAP to the UML kernel >> process, which handles it. The advantage of SKAS0 over TT is that >> memory management syscalls allow the separation of kernel and process >> address space, but every other syscall needs to be handled exactly as >> in TT: e.g., open() needs to map paths using the UML filesystem, etc. >> Right? > > A little off the rails here - in TT mode, there is one address space > in which userspace runs, on every context switch, that address space > needs to be completely remapped in order to become the memory of the > switched-in process. > > In SKAS, every UML process has a host address space, and UML process > context switching is done by the host, at hardware speed. > >> Now a final question: according to the above `ps` output, the shared >> memory among UML processes is ~13GB each. If the above is correct, >> only the UML kernel process should have large shared memory. Is this >> due to `top` misreporting shared memory occupation? (CentOS 5.x w/ >> stock kernel) Or could it be rather a feature of the program that was >> running in the UML? (a data-intensive scientific application) > > I can't find any documentation of the exact meaning of SHR, but I'd > guess that it's looking at MAP_SHARED pages, which for a UML process, > is everything. No utilities are good at accounting for shared > memory. If you just add up the numbers, you end up far away from > reality. > > Jeff > > ------------------------------------------------------------------------------ > Cloud Services Checklist: Pricing and Packaging Optimization > This white paper is intended to serve as a reference, checklist and point > of > discussion for anyone considering optimizing the pricing and packaging > model > of a cloud services business. Read Now! > http://www.accelacomm.com/jaw/sfnl/114/51491232/ > _______________________________________________ > User-mode-linux-user mailing list > User-mode-linux-user@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user > ------------------------------------------------------------------------------ Cloud Services Checklist: Pricing and Packaging Optimization This white paper is intended to serve as a reference, checklist and point of discussion for anyone considering optimizing the pricing and packaging model of a cloud services business. Read Now! http://www.accelacomm.com/jaw/sfnl/114/51491232/ _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
