Xen devel - Dec 2008 - [RFC][PATCH 0/4] Modification of credit scheduler

Hi all,

I accepted George''s suggestion and divided previous patch into the
following 4 patches.

1. Subtract credit consumed accurately and shorten cpu time per one credit
2. Change the handling of credits over upper bound
3. Balance credits of each vcpu of a domain
4. Introduce boost credit for latency-sensitive domain

But I''ll post the fourth patch next week.

Please review these patches.
Any comments are appreciated.

Best regards,
Naoki Nishiguchi


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

By applying this patch, the credit scheduler subtracts accurately credit
consumed and sets correctly priority.
CSCHED_CREDITS_PER_TICK is changed from 100 to 10000, because vcpu''s
credit is subtracted in csched_schedule().

Best regards,
Naoki Nishiguchi


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

By applying this patch, the credit scheduler don''t reset
vcpu''s credit
(set to 0) when the credit would be over upper bound. And it prevents a
vcpu from missing becoming active.

Best regards,
Naoki Nishiguchi


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

By applying this patch, the credit scheduler balances credits of each
active vcpu of a domain.

Best regards,
Naoki Nishiguchi



_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

I forgot to attach.

NISHIGUCHI Naoki wrote:
> By applying this patch, the credit scheduler don''t reset
vcpu''s credit
> (set to 0) when the credit would be over upper bound. And it prevents a
> vcpu from missing becoming active.
> 
> Best regards,
> Naoki Nishiguchi
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

The attached two patches need previous patches(1-3).
  credit_boost_xen.patch  : modification to xen hypervisor
  credit_boost_tools.patch: modification to tools

By applying these two patches, boost credit is introduced to the credit
scheduler. The credit scheduler comes to be able to give priority to
latency-sensitive domain.

In order to set a domain to latency-sensitive domain, you enable boost
credit of the domain. There is two method.

1. Using xm command, set upper bound value of boost credit of the
domain. It is specified by not the value of credit but the millisecond.
It is named max boost period.
  e.g. domain:0, max boost period:100ms
    xm sched-bcredit -d 0 -m 100

2. Using xm command, set upper bound value of boost credit of the domain
and set boost ratio. Boost ratio is ratio to one CPU that is used for
distributing boost credit. Boost credit corresponding to boost ratio is
distributed in place of credit.
  e.g. domain:0, max boost period:500ms, boost ratio:80(80% to one CPU)
    xm sched-bcredit -d 0 -m 500 -r 80


Best regards,
Naoki



_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel