On 07/02/2009 12:41 AM, Erik Jacobson wrote:
I wanted to post in to the thread the lastest test run.
Avi Kivity provided some ideas to try. I had mixed luck. I'd like to try
this again if we have any thoughts on the vpid/ept issue, or any other
ideas for drilling down on this. Avi Kivity mentioned LVM in the thread.
I continued to just export the whole /dev/sdb to the guest. I'm happy to
try LVM in some form if we think it would help?
Exporting an entire drive is even better than LVM (in terms of
performance; flexibility obviously suffers). Just make sure to use
cache=none (which I see in your command line below).
* I could NOT find vpid and ept parameters on the host. They weren't here:
/sys/module/kvm_intel/parameters
nor here
/sys/module/kvm/parameters
So the check for those parameters resulted in no information.
Didn't see them elsewhere either:
# pwd
/sys
# find . -name vpid -print
# find . -name ept -print
Apparently the parameters were only exposed in 2.6.30. Previously they
were only available during modprobe. Since you're using nehalem, let's
assume they're set correctly (since that's the default).
I had done some stuff to set up the test including a build I didn't count.
GUEST time (make -j12&& make -j12 modules), work area disk no cache param
--------------------------------------------------------------------------
kvm_stat output BEFORE running this test:
kvm statistics
efer_reload 13 0
exits 27145076 1142
fpu_reload 1298729 0
halt_exits 2152011 189
halt_wakeup 494689 123
host_state_reload 4998646 837
hypercalls 0 0
insn_emulation 10165593 302
insn_emulation_fail 0 0
invlpg 0 0
io_exits 2096834 643
irq_exits 6469071 8
irq_injections 4765189 190
irq_window 279385 0
largepages 0 0
mmio_exits 0 0
mmu_cache_miss 18670 0
mmu_flooded 0 0
mmu_pde_zapped 0 0
mmu_pte_updated 0 0
mmu_pte_write 10440 0
mmu_recycled 0 0
Nice and quiet.
qemu-kvm command:
/usr/bin/qemu-kvm -M pc -m 4096 -smp 8 -name f11-test -uuid b7b4b7e4-9c07-22aa-0c95-d5c8a24176c5 -monitor pty -pidfile /var/run/libvirt/qemu//f11-test.pid -drive file=/var/lib/libvirt/images/f11-test.img,if=virtio,index=0,boot=on -drive file=/dev/sdb,if=virtio,index=1 -net nic,macaddr=54:52:00:46:48:0e,model=virtio -net user -serial pty -parallel none -usb -usbdevice tablet -vnc cct201:1 -soundhw es1370 -redir tcp:5555::22
-usbdevice tablet is known to cause large interrupt loads. I suggest
dropping it. If it helps your vnc session, drop your vnc client and use
vinagre instead.
test run timing:
real 12m36.165s
user 27m28.976s
sys 8m32.245s
12 minutes real vs 35 cpu minutes -> scaling only 3:1 on smp 8.
kvm_stat output after this test run
kvm statistics
efer_reload 13 0
exits 47097981 2003
fpu_reload 2168308 0
halt_exits 3378761 301
halt_wakeup 707171 241
host_state_reload 7545990 1538
hypercalls 0 0
insn_emulation 17809066 462
insn_emulation_fail 0 0
invlpg 0 0
io_exits 2801221 1232
irq_exits 11959063 7
irq_injections 8395980 304
irq_window 531641 3
largepages 0 0
mmio_exits 0 0
mmu_cache_miss 28419 0
mmu_flooded 0 0
mmu_pde_zapped 0 0
mmu_pte_updated 0 0
mmu_pte_write 10440 0
mmu_recycled 7193 0
Nice and quiet too, but what's needed is kvm_stat (or kvm_stat -1)
during the run. Many of the 47M exists are unaccounted for, there's a
lack in the stats gathering code.
vmstat 1 on host and guest during the run would also help.
HOST time (make -j12&& make -j12 modules) with no guest running
----------------------------------------------------------------
real 6m50.936s
user 29m12.051s
sys 5m50.867s
35 minutes cpu run on 7 minutes real time, so scaling 1:7. User time
almost the same, system time different but not enough to account for the
large difference in run time.
I'm due to get my own Nehalem next week, I'll try to reproduce your
results here.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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