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[Xen-devel] [PATCH][RFC] consider weight for vcpu-pin case

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Subject: [Xen-devel] [PATCH][RFC] consider weight for vcpu-pin case
From: Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>
Date: Wed, 09 May 2007 11:49:53 +0900
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This patch intends to consider weight for vcpu-pin case.
(in other words, pcpu.credit > 30msec case.) 
In this case, weight parameter does not work appropriately.
By applying this patch, weight parameter works.

This patch consists 3-parts
1)Weight Calculation for vcpupin
  csched_consider_vcpupin()  (add)

2)Credit Balance Calculation for vcpupin  
  csched_consider_vcpupin_credit_balance()  (add)

3)Other credit correction factor calculation.
  csched_acct()  (modified like variable csched_corr_factor)

For test
If you want to test this patch, please test like following configuration
at 4pcpu machine.
Dom1 vcpu0.0-1 vcpu1.0-1 weight 256
Dom2 vcpu0.0-1 vcpu1.0-1 weight 512
N.B.)0-1 means pininfo(xm vcpu-pin)
If this patch does not applied, xentop shows each cpu 100%.
But If you use this patch, xentop shows 66%, 133% for each domain.

Discussion Points
1) many loop is permitted?
2) arithmetic divide is still remain 4 points for each vcpu.
3) Is it enough tuned?(Need more tune) 

Any comments will be appreciated.

this problem is already questioned six month ago.
At this moment, I think this effect is very low.
But a month ago, somebody suggested me this issue is important.
(SMP like boot 8cpu with 2domain in 1pcpu share, weight does not effect.
This also effects NUMA system weight.)
Atsushi SAKAI

Attachment: vcpupin_weight_consider.patch
Description: Binary data

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