[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Credit scheduler
Hi Prabha Please check do_softirq in assembler. for x86 call do_softirq is in. And usually do_softirq is executed at the end of system call. Thanks Atsushi SAKAI pak333@xxxxxxxxxxx wrote: > Thanks for the explanation, i am not sure i understood it correctly. > > > when does softirq get set. So when softirq is set a processor enters the > scheduler every 3 micro secs? where in the source code is this handled. > please could you send me some pointers > > thanks > -Prabha > > > > > -------------- Original message -------------- > From: Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx> > > > Hi, Prabha > > > > 30msec is the maximum time slice. > > And I guess your 3 microsecond is the response after > > SCHEDULE_SOFTIRQ is set. > > As you know, > > If SCHEDULE_SOFTIRQ is set, > > it waits softirq calls schedule(). (this time interval is 3microsec) > > > > And I/O intensive has higher priority than CPU intensive. > > So I/O intensive job is first dispatched domain in runq. > > This is because latency improvement for I/O intensive guest. > > > > So your behavior is not strange. > > > > Thanks > > Atsushi SAKAI > > > > > > pak333@xxxxxxxxxxx wrote: > > > > > Hi > > > > > > I have noticed that VMs are typically spending 3 microsecs or less before > > > they > > are being prempted. I thought that the credit schduler time slice was 30 > > ms. I > > have 4 VMs running and they are all cpu intensive except for 1 (which is IO > > intensive) but having a VM spend max 3 micro secs before being kicked out > > seems > > strange. > > > > > > Is there something else going on that i am not aware of. Is the time > > > slice > > really 30 millisecs? I am using default parameters of the credit scheduler. > > > > > > Thanks > > > -Prabha > > > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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