Technical arguments aside, I thought that people feel the stop/resume model of Activity important to Sugar.
If so, I think the stop/resume model does invite the idea of limiting to one instance of activity at a time. Two parallel Write sessions? Then, we might as well consider to switch to the documents and applications model. -- Yoshiki At Wed, 29 Oct 2008 20:23:48 -0400, Benjamin M. Schwartz wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Deepak Saxena wrote: > > On the XO, if we try to edit two documents concurrently on Write, we should > > in my opinion only have on instance of write running which can switch > > quickly > > between document objects so the user percieves it as two separate instances. > > I disagree strongly, for several reasons. > > 1. Bitfrost requires that each instance be isolated from every other. > Each instance only has access to the Journal items to which the user has > explicitly granted it access. Allowing multiple "apparent instances" to > share data behind the scenes represents a privilege-combining attack. > This is especially apparent if one instance has been launched with > P_NETWORK but not P_CAMERA, and the other has been launched with the > reverse privileges. > > 2. A key feature of the Sugar Activity system is that writing Activities > is _easy_. The goal is to minimize the amount of work required to write > an Activity. Asking Activity authors to juggle multiple virtual instances > creates tremendous complexity that is likely to produce bugs even when > performed by experts (e.g. Browse), for no user-visible gain. > > 3. Two separate Activity instances already share a great deal, because > the Linux kernel automatically uses CoW to keep only one copy of read-only > memory needed by multiple processes. Each Write instance uses no CPU when > idle, so RAM is the only overhead. > > As a matter of efficiency, there is certainly more we can do to decrease > the memory overhead of running multiple instances. People are working to > improve the efficiency of our X icon caching system and python launcher. > Even better would be to work on the python interpreter upstream to improve > memory usage and reduce the dirtying of pages that could be shared. > > - --Ben > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v2.0.9 (GNU/Linux) > > iEYEARECAAYFAkkI/pQACgkQUJT6e6HFtqTCBgCfQg0RDoRC38U1mWmwzQSgfxJe > i+AAn1nWN9EyvkYNJGSniZ5xfOxviyRd > =Upkp > -----END PGP SIGNATURE----- > _______________________________________________ > Devel mailing list > [email protected] > http://lists.laptop.org/listinfo/devel _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
