alex wrote:
the following patchs provide an extra control(besides the control of
Linux scheduler) over the execution of vcpu threads.
In this patch, Xen's credit
scheduler(http://wiki.xensource.com/xenwiki/CreditScheduler) is used.
User can use "cat" and
"echo" command to view and control a guest os' credit.
e.g.,
[root@localhost ~]# echo "weight=500" > /proc/kvm/12345
will change the credit of guest whose qemu process has the pid 12345 to be 500.
The patch consists of 3 parts:
1. modification to the standard KVM
2. modification to the Xen scheduler
3. helper functions
Just wondering, was it not possible to introduce a new scheduling class
in the current scheduler? My impression was that the current scheduler
was fairly modular and should allow this.
-Andrew
However, some are unnecessary in the latest Linux kernel.
The difficulties in the ports lie in:
1. Linux does not provide timer mechanism that the timer function is
bind to a dedicate CPU:
in case of one cpu receives another cpu's schedule timer
expiration, IPI is used to relay it.
2. before linux 2.6.27, the smp_call_function_xxx() can not be re-entered.
if kvm is sending ipi at the time of relaying timer expiration
information, deadlock would occur in kernel versions below 2.6.27
In my implementation, tasklets are used to run the function of
scheduling, and kernel thread is used to send IPI(in kernels above
2.6.27, this is unnecessary)
Originally, this code is developed at the release version of KVM-83.
In order to post it, I ported to the latest .git tree. As a result,
modifications to files like external-module-compat-comm.h are omited.
NOTE:
1. Because my not having an AMD machine, only intel platforms are tested.
2. Because sched_setaffinity() is used (while Linux does not export
this symbol), the way of loading kvm modules are changed to be
./myins <directory that holds the kvm.ko and kvm-intel.ko>
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