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Stefano Stabellini
82fde4fa36
Introduce new Xen command line parameter called "vwfi", which stands for virtual wfi. The default is "trap": Xen traps guest wfi and wfe instructions. In the case of wfi, Xen calls vcpu_block on the guest vcpu; in the case of guest wfe, Xen calls vcpu_yield on the guest vcpu. The behavior can be changed by setting vwfi to "native", in that case Xen doesn't trap neither wfi nor wfe, running them in guest context. The result is strong reduction in irq latency (from 5000ns to 2000ns, measured using https://github.com/edgarigl/tbm, the physical timer, and 1 pcpu dedicated to 1 vcpu). The downside is that the scheduler thinks that the guest is busy when actually is sleeping, leading to suboptimal scheduling decisions. Signed-off-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com> Reviewed-by: Julien Grall <julien.grall@arm.com>
xen-bugtool =========== The xen-bugtool command line application will collate the Xen dmesg output, details of the hardware configuration of your machine, information about the build of Xen that you are using, plus, if you allow it, various logs. The information collated can either be posted to a Xen Bugzilla bug (this bug must already exist in the system, and you must be a registered user there), or it can be saved as a .tar.bz2 for sending or archiving. The collated logs may contain private information, and if you are at all worried about that, you should not use this tool, or you should explicitly exclude those logs from the archive. xen-bugtool is wholly interactive, so simply run it, and answer the questions.