Messages in this thread | | | From | "Styner, Douglas W" <> | Date | Mon, 27 Apr 2009 11:38:08 -0700 | Subject | Discrepancies between Oprofile and vmstat |
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We are using an OLTP-type workload on a fully saturated system and have begun seeing a discrepancy between the output of oprofile and vmstat on upstream kernels that was first seen with the 2.6.27 kernel.
Workload: OLTP database workload using QLogic FC cards with MSI-X enabled doing ~50,000 IOPS
Oprofile (v0.9.3) collection methodology: opcontrol --init opcontrol --vmlinux=/usr/src/linux-`uname -r`/vmlinux opcontrol -e=CPU_CLK_UNHALTED:80000 -e=LLC_MISSES:6000 opcontrol --start-daemon sleep 5 opcontrol --start sleep 60 opcontrol --stop opcontrol --save=$1 opcontrol --deinit
Function classification: Modules vmlinux and *.ko = kernel, all others = user.
Results (2.6.30-rc3 kernel): vmstat reports ~75% user, 25% kernel oprofile reports 70.3808% user, 29.6142% kernel
Using another profiling tool to confirm, we see 74.784% user, 25.174% kernel.
Doug Styner douglas.w.styner@intel.com
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