hi
A network application (with its kernel network driver),
it uses 5-8% cpu(I have tested it on kernel 2.6.34, seen from 'top'),
but I got 40% cpu usage on kernel 2.6.36
so that I tried oprofile to see what happen:
opcontrol --vmlinux=/home/kho56208/linux-2.6.36.4/vmlinux
...
compared with profile result on kernel 2.6.34, the
"mwait_idle_with_hints" got a higher "CPU_CLK_UNHALTED " event sample,
what does it mean? any clue?
CPU: Intel Architectural Perfmon, speed 2666.01 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a
unit mask of 0x00 (No unit mask) count 100000
samples % symbol name
115595 17.5906 mwait_idle_with_hints
27098 4.1236 __alloc_skb
25992 3.9553 __slab_free
25707 3.9120 __netif_receive_skb
18784 2.8584 __kmalloc_node_track_caller
18223 2.7731 get_partial_node
17860 2.7178 add_partial
17662 2.6877 kfree
17655 2.6866 kmem_cache_alloc_node
...
(kernel 2.6.34):
CPU: Intel Architectural Perfmon, speed 1600 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a
unit mask of 0x00 (No unit mask) count 100000
samples % symbol name
389859 7.9392 mwait_idle_with_hints
306288 6.2374 kfree
273832 5.5764 kmem_cache_alloc_node
268486 5.4675 netif_receive_skb
219047 4.4607 __alloc_skb
192371 3.9175 kmem_cache_free
138046 2.8112 memcpy
133959 2.7280 dev_gro_receive
system wide profile (2.6.36)
"MY_APPLICATION" got 40% cpu usage,why it is only 0.8799% seen from oprofile?
(the machine has 12 cores, and the oprofile is to measure all cores
CPU: Intel Architectural Perfmon, speed 2666.01 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a
unit mask of 0x00 (No unit mask) count 100000
CPU_CLK_UNHALT...|
samples| %|
------------------
656980 40.1202 vmlinux
473114 28.8919 vmlinux
298978 18.2579 MY_KERNEL_DRIVER
165838 10.1273 ixgbe
14408 0.8799 MY_APPLICATION
10443 0.6377 libc-2.11.1.so
8251 0.5039 processor
4658 0.2845 oprofiled
3103 0.1895 libpthread-2.11.1.so
1209 0.0738 oprofile
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