From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Ehrhardt Date: Fri, 04 Apr 2008 11:01:41 +0000 Subject: [kvm-ppc-devel] Oprofile kvmppc - mini howto and restrictions (atm) Message-Id: <47F60A95.4030401@linux.vnet.ibm.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: kvm-ppc@vger.kernel.org to sample you can use: opcontrol --vmlinux=3D/root/vmlinux.host --session-dir=3D/mnt/usb/oprofile/ # I use that session dir to separate measurements e.g. so you can store sev= eral measurements to analyze later on opcontrol --start # starts profiling opcontrol --stop # stops but not ends profiling opcontrol --shutdown # stops profiling and ensures all data is flushed to t= he samples dir Example: bash-3.00# opcontrol --vmlinux=3D/root/vmlinux.host --session-dir=3D/mnt/us= b/oprofile/ bash-3.00# opcontrol --start Using 2.6+ OProfile kernel interface. Reading module info. Using log file /mnt/usb/oprofile//samples/oprofiled.log Daemon started. Profiler running. ### now I start the guest in another window - boot from ramdisk image with = virtio-block&net enabled, shutdown when bootet, killed when on halt bash-3.00# opcontrol --shutdown Stopping profiling. Killing daemon. # you can now use opreport to analyze the date, use --session-dir to specif= y what you want to analyze. That way for the start I sampled a boot&halt and in another sample whats st= ill going on when the guest idles 2 minutes at the login prompt =3D> Reports in the following mails ### important ### Note the bad thing, atm oprofile on ppc440 seems not to have hw perf counte= rs available. Therefore it is covered with the fallback timer-interrupt. Bu= t this has drawbacks: =3D>from the oprfile info page: "In 2.6 kernels on CPUs without OProfile support for the hardware performan= ce counters, the driver falls back to using the timer interrupt for profili= ng. Like the RTC mode in 2.4 kernels, this is not able to profile code that= has interrupts disabled. Note that there are no configuration parameters f= or setting this, unlike the RTC and hardware performance counter setup." So oprofile works but without real cpu perf counters it will be nearly usel= ess, because we have interrupts disabled in most code we want to profile. I= need to look out for some beta support (or write my own) for ppc440 cpu pe= rf counters to enable that for us :( --=20 Gr=FCsse / regards,=20 Christian Ehrhardt IBM Linux Technology Center, Open Virtualization ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ kvm-ppc-devel mailing list kvm-ppc-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-ppc-devel