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Description of problem: * either blktrace guesses the number of CPUs incorrectly or it is not able to run on more 32 CPUs Version-Release number of selected component (if applicable): RHEL-6.7 blktrace-1.0.1-7.el6.ppc64 kernel-2.6.32-573.el6.ppc64 kernel-bootwrapper-2.6.32-573.el6.ppc64 kernel-devel-2.6.32-573.el6.ppc64 kernel-firmware-2.6.32-573.el6.noarch kernel-headers-2.6.32-573.el6.ppc64 How reproducible: always Steps to Reproduce: # dmesg | grep -i cpus Partition configured for 64 cpus. Initializing cgroup subsys cpuset Brought up 32 CPUs Node 0 CPUs: 0-31 # mount -t debugfs debugfs /sys/kernel/debug/ #blktrace -w 1 -d /dev/sda Actual results: FAILED to start thread on CPU 32: 22/Invalid argument FAILED to start thread on CPU 33: 22/Invalid argument FAILED to start thread on CPU 34: 22/Invalid argument FAILED to start thread on CPU 35: 22/Invalid argument FAILED to start thread on CPU 36: 22/Invalid argument FAILED to start thread on CPU 37: 22/Invalid argument FAILED to start thread on CPU 38: 22/Invalid argument FAILED to start thread on CPU 39: 22/Invalid argument FAILED to start thread on CPU 40: 22/Invalid argument FAILED to start thread on CPU 41: 22/Invalid argument FAILED to start thread on CPU 42: 22/Invalid argument FAILED to start thread on CPU 43: 22/Invalid argument FAILED to start thread on CPU 44: 22/Invalid argument FAILED to start thread on CPU 45: 22/Invalid argument FAILED to start thread on CPU 46: 22/Invalid argument FAILED to start thread on CPU 47: 22/Invalid argument FAILED to start thread on CPU 48: 22/Invalid argument FAILED to start thread on CPU 49: 22/Invalid argument FAILED to start thread on CPU 50: 22/Invalid argument FAILED to start thread on CPU 51: 22/Invalid argument FAILED to start thread on CPU 52: 22/Invalid argument FAILED to start thread on CPU 53: 22/Invalid argument FAILED to start thread on CPU 54: 22/Invalid argument FAILED to start thread on CPU 55: 22/Invalid argument FAILED to start thread on CPU 56: 22/Invalid argument FAILED to start thread on CPU 57: 22/Invalid argument FAILED to start thread on CPU 58: 22/Invalid argument FAILED to start thread on CPU 59: 22/Invalid argument FAILED to start thread on CPU 60: 22/Invalid argument FAILED to start thread on CPU 61: 22/Invalid argument FAILED to start thread on CPU 62: 22/Invalid argument FAILED to start thread on CPU 63: 22/Invalid argument Expected results: # cat /sys/devices/system/cpu/online 0-31 # cat /sys/devices/system/cpu/offline 32-1023 * blktrace runs on all CPUs which are online and it doesn't complain about the others
So the root problem is that it is trying to start threads on offline CPUs?
commit 80c4041b2e7a7d5afb75df563bf51bb27773c095 Author: Abutalib Aghayev <agayev> Date: Tue Feb 9 08:17:50 2016 -0700 blktrace: Use number of online CPUs Currently, blktrace uses _SC_NPROCESSORS_CONF to find out the number of CPUs. This is a problem, because if you reduce the number of online CPUs by passing kernel parameter maxcpus, then blktrace fails to start with the error: FAILED to start thread on CPU 4: 22/Invalid argument FAILED to start thread on CPU 5: 22/Invalid argument ... The attached patch fixes it to use _SC_NPROCESSORS_ONLN. Signed-off-by: Jens Axboe <axboe>
Postponing to rhel-6.9 as it is too late to address this bug in rhel-6.8.
Sadly I don't think we'll be able to ship this fix at this point in rhel6.