Re: [Xen-devel] Question on xen schedulers

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 15/11/06 4:48 pm, "Schmidt Werner" <Werner.Schmidt@xxxxxxxxxxxxxxxxx> wrote:

> 'credit' is now the (only) recommended scheduler and the others ('bvt', 'sedf') are already removed from the latest Xen 3.0 sources or will be removed in the future.
> Now, 'credit' is designed for an optimum utilisation of a SMP system and may be really the best scheduler for this purpose. But i think this is not the only useful scenario for the usage of Xen; there maybe other scenarios with other demands, e.g. 'soft' real-time systems and/or single processor systems.
> If i remember correctly, one of the major advantages mentioned in the first announcements of Xen 3.0 was the support of multiple schedulers (for different purposes). Could give anyone the reasons why this approach is not longer valid and what is the reason to kick out the already existing more 'real-time friendly' schedulers, especially sedf ?

The main reason is that noone has time to support them and they are buggy. If there is demand for SEDF then we may keep it in the tree, but unless someone steps up to maintain it then bugs will not be fixed (for example, it exhibits weird behaviours with some settings of the scheduling parameters). However I understand this may not matter for users who have found reasonable parameter settings which work for them.

 -- Keir



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