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Diffstat (limited to 'docs/man/xm.pod.1')
| -rw-r--r-- | docs/man/xm.pod.1 | 123 |
1 files changed, 103 insertions, 20 deletions
diff --git a/docs/man/xm.pod.1 b/docs/man/xm.pod.1 index a49675eaaa..75bf431146 100644 --- a/docs/man/xm.pod.1 +++ b/docs/man/xm.pod.1 @@ -488,49 +488,126 @@ explainitory. =head1 SCHEDULER SUBCOMMANDS +Xen ships with a number of domain schedulers, which can be set at boot +time with the I<sched=> parameter on the Xen command line. By +default I<sedf> is used for scheduling. + FIXME: we really need a scheduler expert to write up this section. =over 4 -=item I<sched-bvt> <Parameters> +=item I<sched-bvt> <mcuadv> <warpback> <warpvalue> <warpl> <warpu> + +Performs runtime adjustments to the default parameters for the +Borrowed Virtual Time (BVT) scheduler. For full information on the +BVT concept, please consult the base paper listed in the B<SEE ALSO> +section. Set Borrowed Virtual Time (BVT) scheduler parameters. There are five -parameters, which are given in order below. +required parameters, which are given in order below. + +B<PARAMETERS> =over 4 -Parameters: +=item L<mcuadv> + +The MCU (Minimum Charging Unit) advance determines the proportional +share of the CPU that a domain receives. It is set inversely +proportionally to a domain's sharing weight. + +=item L<warpback> + +The amount of `virtual time' the domain is allowed to warp backwards. + +=item L<warpvalue> + - mcuadv - Minimum Charging Unit (MCU) advance. - warpback - Warp back time allowed. - warpvalue - Warp value. - warpl - Warp maximum limit. - warpu - Unwarped minimum limit. +Warp value + +=item L<warpl> + +The warp limit is the maximum time a domain can run warped for. + +=item L<warpu> + +The unwarp requirement is the minimum time a domain must run unwarped +for before it can warp again. =back =item I<sched-bvt-ctxallow> <Allow> -Sets the BVT scheduler's context switch allowance. Allow is the -minimum time slice allowed to run before being pre-empted. +Sets the BVT scheduler's context switch allowance. -=item I<sched-sedf> <Parameters> +The context switch allowance is similar to the ``quantum'' in +traditional schedulers. It is the minimum time that a scheduled domain +will be allowed to run before being preempted. -Set simple sEDF scheduler parameters. Use the following parametersin -order. +=item I<sched-sedf> <period> <slice> <latency-hint> <extratime> <weight> + +Set Simple EDF scheduler parameters. This scheduler provides weighted +CPU sharing in an intuitive way and uses realtime-algorithms to ensure +time guarantees. For more information see +docs/misc/sedf_scheduler_mini-HOWTO.txt in the Xen distribution. + +B<PARAMETERS> =over 4 -Parameters: +=item I<period> + +The normal EDF scheduling usage in nanosecs + +=item I<slice> - period - in nanoseconds - slice - in nanoseconds - latency-hint - scaled period if domain is doing heavy I/O - extratime - flag for allowing domain to run in extra time. - weight - another way of setting cpu slice. +The normal EDF scheduling usage in nanosecs + +FIXME: these are lame, should explain more. + +=item I<latency-hint> + +Scaled period if domain is doing heavy I/O. + +=item I<extratime> + +Flag for allowing domain to run in extra time. + +=item I<weight> + +Another way of setting cpu slice. =back +B<EXAMPLES> + +normal EDF (20ms/5ms): + + xm sched-sedf <dom-id> 20000000 5000000 0 0 0 + +best-effort domains (i.e. non-realtime): + + xm sched-sedf <dom-id> 20000000 0 0 1 0 + +normal EDF (20ms/5ms) + share of extra-time: + + xm sched-sedf <dom-id> 20000000 5000000 0 1 0 + +4 domains with weights 2:3:4:2 + + xm sched-sedf <d1> 0 0 0 0 2 + xm sched-sedf <d2> 0 0 0 0 3 + xm sched-sedf <d3> 0 0 0 0 4 + xm sched-sedf <d4> 0 0 0 0 2 + +1 fully-specified (10ms/3ms) domain, 3 other domains share available +rest in 2:7:3 ratio: + + xm sched-sedf <d1> 10000000 3000000 0 0 0 + xm sched-sedf <d2> 0 0 0 0 2 + xm sched-sedf <d3> 0 0 0 0 7 + xm sched-sedf <d4> 0 0 0 0 3 + =back =head1 VIRTUAL DEVICE COMMANDS @@ -541,7 +618,7 @@ event. =over 4 -=item I<block-attach <DomId> <BackDev> <FrontDev> <Mode> [BackDomId] +=item I<block-attach> <DomId> <BackDev> <FrontDev> <Mode> [BackDomId] Create a new virtual block device @@ -590,6 +667,12 @@ Delete a vnet. B<xmdomain.cfg>(5) +BVT scheduling paper: K.J. Duda and D.R. Cheriton. Borrowed Virtual +Time (BVT) scheduling: supporting latency-sensitive threads in a +general purpose scheduler. In proceedings of the 17th ACM SIGOPS +Symposium on Operating Systems principles, volume 33(5) of ACM +Operating Systems Review, pages 261-267 + =head1 AUTHOR Sean Dague <sean at dague dot net> |