Date: Fri, 23 Nov 2012 16:15:17 +0300 From: Alex Chistyakov <alexclear@gmail.com> To: freebsd-emulation@freebsd.org Subject: VirtualBox 4.2.4 on FreeBSD 9.1-PRERELEASE problem: VMs behave very different when pinned to different cores Message-ID: <CA%2Bkq2xvh3j5CM7UzRVfXCeLhHwpTY%2B_M7dCJx0c27NtV8EVJwg@mail.gmail.com>
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Hello, I am back with another problem. As I discovered previously setting a CPU affinity explicitly helps to get decent performance on guests, but the problem is that guest performance is very different on core #0 and cores #5 or #7. Basically when I use 'cpuset -l 0 VBoxHeadless -s "Name" -v on' to start the VM it is barely usable at all. The best performance results are on cores #4 and #5 (I believe they are the same physical core due to HT). #7 and #8 are twice as slow as #5, #0 and #1 are the slowest and other cores lay in the middle. If I disable a tickless kernel on the guest running on #4 or #5 it becomes as slow as a guest running on #7 so I suspect this is a timer-related issue. I also discovered that there are quite a lot of system interrupts on slow guests (%si is about 10-15) but Munin does not render them on its CPU graphs for some reason. All my VMs are on cores #4 and #5 right now but I want to utilize other cores too. I am not sure what to do next, this looks like a VirtualBox bug. What can be done to solve this? Thank you! -- SY, Alex
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