[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] More about Resource Scheduling and Accounting
> -----Original Message----- > From: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx [mailto:xen-devel- > admin@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of cs0u210a@xxxxxxxxxxxxxxx > Sent: Friday, October 10, 2003 10:31 PM > To: xen-devel@xxxxxxxxxxxxxxxxxxxxx > Cc: Keir.Fraser@xxxxxxxxxxxx; Ian.Pratt@xxxxxxxxxxxx > Subject: [Xen-devel] More about Resource Scheduling and Accounting > > Hi, > > Sorry I have been busy with some academic issues since my last email > but > should now focus on Xen with all my time. > > As stated before I would like to work on the Resource Scheduling and > Accounting part (in addition, try to relate a bit to the OS > suspend/resume for > migration), which at the same time will be my honour year project. The > functions/requirements that Ian has mentioned before is still at a high > level. > Hence I would like to know if there are some specific requirements (eg > standard > of interface to other kernel functions and interface for domain0 etc) > that you > would like to mention, especially by the Xen team. I welcome any > comments/suggestions by anyone in the Xen-devel maillist as well, be it > additional features, concepts or designs or anything else. > > A particular question I would like to know is how well the BVT > algorithm is > functioning, and what is the weakness at the moment. In the SOSP 2003 > paper, > 3.3.1 CPU Scheduling mentioned other scheduling algorithms could be > trivially > implemented over the generic abstraction and per-domain scheduling > parameters > can be adjusted....in Domain0. First, could you tell me all files related > to > the scheduling algorithm and the abstraction, this would greatly help me > to > start. Second, is it true that per-domain parameters can be ajusted by > Domain0? > How well is this performing? What are the things need to be improved? in xen the scheduler is implemented in common/schedule.c. sched.h includes the task structure and common ac_timer.c provides a timer interface. The interface to changes scheduling parameters is exported to dom via common/dom0_ops.c and in via a hypercall (HYPERCALL_dom0_op). See xi_sched_domain.c for an example. A new scheduler mainly requires changes to schedule.c but also to dom0_ops.c to change the parameters passed from domain0. BVT provides prop. fairness. That works fine. BVT also has a mechanism to decrease wakeup latencies (warping). This currently happens if a domain receives an event. As a domain in the current version receives a periodic ticker interrupt this means it gets warped periodically (subject to the limits provided by BVT). This also means that if a more important event arrives (e.g., network packet) a domain might not be warped. This may be a problem. I have patches which hopefully solve this (under test at the moment). These patches disable the periodic ticker and on the xenolinux side are based on-demand timer patches IBM provides for the s390 port of Linux. I'd suggest to try to implement one or more different scheduler, maybe one offering absolute shares, rather than prop. fairness. As we say in the paper this should be quite straight forward. Another limitation of the current scheduler is that it doesn't provide migration of domains between CPUs. A domain is currently assigned a fixed CPU. migrating it to others CPUs when that CPU is busy would be useful. Maybe you want to look at "take scheduling" (sorry don't have a reference handy) for network scheduling see Keir's recent checkin. Rolf > > One more thing, I wonder if you can provide me some pointers to other > materials you think will be useful for the work such as research papers, > texts, > how-to, source codes etc. > > Many thanks, > > Yan-Ching CHU > > > > > > > > ------------------------------------------------------- > This SF.net email is sponsored by: SF.net Giveback Program. > SourceForge.net hosts over 70,000 Open Source Projects. > See the people who have HELPED US provide better services: > Click here: http://sourceforge.net/supporters.php > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/xen-devel ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. SourceForge.net hosts over 70,000 Open Source Projects. See the people who have HELPED US provide better services: Click here: http://sourceforge.net/supporters.php _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/xen-devel
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