On 03/21/2010 02:13 AM, Sebastian Hetze wrote:
Hi *,
in an 6 CPU SMP guest running on an host with 2 quad core
Intel Xeon E5520 with hyperthrading enabled
we see one or more guest CPUs working in a very strange
pattern. It looks like all or nothing. We can easily identify
the effected CPU with xosview. Here is the mpstat output
compared to one regular working CPU:
mpstat -P 4 1
Linux 2.6.31-16-generic-pae (guest) 21.03.2010 _i686_ (6 CPU)
00:45:19 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle
00:45:20 4 0,00 100,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00
00:45:21 4 0,00 100,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00
00:45:22 4 0,00 100,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00
00:45:23 4 0,00 100,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00
00:45:24 4 0,00 66,67 0,00 0,00 0,00 33,33 0,00 0,00 0,00
00:45:25 4 0,00 100,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00
00:45:26 4 0,00 100,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00
Looks like the guest is only receiving 3-4 timer interrupts per second,
so time becomes quantized.
Please run the attached irqtop in the affected guest and report the results.
Is the host overly busy? What host kernel, kvm, and qemu are you
running? Is the guest running an I/O workload? if so, how are the disks
configured?
--
error compiling committee.c: too many arguments to function
#!/usr/bin/python
import curses
import sys, os, time, optparse
def read_interrupts():
irq = {}
proc = file('/proc/interrupts')
nrcpu = len(proc.readline().split())
for line in proc.readlines():
vec, data = line.strip().split(':', 1)
if vec in ('ERR', 'MIS'):
continue
counts = data.split(None, nrcpu)
counts, rest = (counts[:-1], counts[-1])
count = sum([int(x) for x in counts])
try:
v = int(vec)
name = rest.split(None, 1)[1]
except:
name = rest
irq[name] = count
return irq
def delta_interrupts():
old = read_interrupts()
while True:
irq = read_interrupts()
delta = {}
for key in irq.keys():
delta[key] = irq[key] - old[key]
yield delta
old = irq
label_width = 30
number_width = 10
def tui(screen):
curses.use_default_colors()
curses.noecho()
def getcount(x):
return x[1]
def refresh(irq):
screen.erase()
screen.addstr(0, 0, 'irqtop')
row = 2
for name, count in sorted(irq.items(), key = getcount, reverse = True):
if row >= screen.getmaxyx()[0]:
break
col = 1
screen.addstr(row, col, name)
col += label_width
screen.addstr(row, col, '%10d' % (count,))
row += 1
screen.refresh()
for irqs in delta_interrupts():
refresh(irqs)
curses.halfdelay(10)
try:
c = screen.getkey()
if c == 'q':
break
except KeyboardInterrupt:
break
except curses.error:
continue
import curses.wrapper
curses.wrapper(tui)
