[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] How to increase timer resolution?
set_timer() and friends are already high-resolution, so long as your system has a local APIC. This is undoubtedly the case if running a multi-processor system. On a uni-processor system you might need to forcibly enable use of the APIC with 'lapic' as a Xen boot parameter. Either way, early during boot you should find a message saying local APIC is found and enabled, or not found, or whatever. -- Keir On 14/9/08 07:06, "Robert Kaiser" <kaiser@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hi everyone, > > I'm using Xen 3.2.1 in my experimental setup, trying to find relationships > between switch frequencies and overheads. For that, it would be good if I > could increase the resolution of the timer (i.e. the one that you access > with set_timer(), stop_timer() and friends). Currently, this seems to be > fixed at 10 milliseconds, but I would like to change it to 1ms or maybe even > down to a few hundred microseconds. I'm aware that this will affect > performance -- that is part of what I'd like to measure. > > Can you experts give me some hints how to do this, i.e. is it just a matter of > giving the kernel the right commandline options (which?), can it be done by > changing a few compile time constants (which? where?), or is there more > involved? > > Ideally, I would implement a new control function by which dom0 could change > the frequency dynamically at run-time, but even having to re-compile Xen > between experiments might be an acceptable approach. However, the code base > is so dauntingly huge for a newbie like myself, I'm having difficulties in > finding the right set-screws. Can anyone help me out? > > Cheers > > Rob _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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