Re: [Crash-utility] [PATCH] runq: make tasks in throttled cfs_rqs/rt_rqs displayed

----- Original Message ----- > > ok. I rewrite the patch and they are tested ok in my box. > > Thanks > Zhang My tests weren't so successful this time, and I also have some questions about the runq -g output. I tested your latest patches on a sample set of 70 dumpfiles whose kernels all use CFS runqueues. In 7 of the 70 "runq -g" tests, the command caused the crash session to fail like so:

In a quick debugging session of your free_task_group_info_array() I printed out the addresses being FREEBUF()'d, and I noted that there were numerous instances of the same address being free twice: static void free_task_group_info_array(void) { int i; for (i = 0; i < tgi_p; i++) { if (tgi_array[i]->name) FREEBUF(tgi_array[i]->name); FREEBUF(tgi_array[i]); } tgi_p = 0; FREEBUF(tgi_array); } I put one of the failing vmlinux/vmcore pairs here for you to debug: http://people.redhat.com/anderson/zhangyanfei

From the debug information above and from my tests, I noticed that it always

Secondly, another question I have is the meaning of the command's output. First, consider this "runq" output: crash> runq CPU 0 RUNQUEUE: ffff8800090436c0 CURRENT: PID: 588 TASK: ffff88007e4877a0 COMMAND: "udevd" RT PRIO_ARRAY: ffff8800090437c8 [no tasks queued] CFS RB_ROOT: ffff880009043740 [118] PID: 2110 TASK: ffff88007d470860 COMMAND: "check-cdrom.sh" [118] PID: 2109 TASK: ffff88007f1247a0 COMMAND: "check-cdrom.sh" [118] PID: 2114 TASK: ffff88007f20e080 COMMAND: "udevd" CPU 1 RUNQUEUE: ffff88000905b6c0 CURRENT: PID: 2113 TASK: ffff88007e8ac140 COMMAND: "udevd" RT PRIO_ARRAY: ffff88000905b7c8 [no tasks queued] CFS RB_ROOT: ffff88000905b740 [118] PID: 2092 TASK: ffff88007d7a4760 COMMAND: "MAKEDEV" [118] PID: 1983 TASK: ffff88007e59f140 COMMAND: "udevd" [118] PID: 2064 TASK: ffff88007e40f7a0 COMMAND: "udevd" [115] PID: 2111 TASK: ffff88007e4278a0 COMMAND: "kthreadd" crash> In the above case, the per-cpu "rq" structure addresses are shown as: CPU 0 RUNQUEUE: ffff8800090436c0 CPU 1 RUNQUEUE: ffff88000905b6c0 And embedded in each of the rq structures above are these two rb_root structures: CFS RB_ROOT: ffff880009043740 (embedded in rq @ffff8800090436c0) CFS RB_ROOT: ffff88000905b740 (embedded in rq @ffff88000905b6c0) And starting at those rb_root structures, the tree of tasks are dumped. Now, your "runq -q" option doesn't show any "starting point" structure address, but rather they just show "CPU 0" and "CPU 1": crash> runq -g CPU 0 CURRENT: PID: 588 TASK: ffff88007e4877a0 COMMAND: "udevd" RT PRIO_ARRAY: ffff8800090437c8 [no tasks queued] CFS RB_ROOT: ffff880009093548 [118] PID: 2110 TASK: ffff88007d470860 COMMAND: "check-cdrom.sh" [118] PID: 2109 TASK: ffff88007f1247a0 COMMAND: "check-cdrom.sh" [118] PID: 2114 TASK: ffff88007f20e080 COMMAND: "udevd" CPU 1 CURRENT: PID: 2113 TASK: ffff88007e8ac140 COMMAND: "udevd" RT PRIO_ARRAY: ffff88000905b7c8 [no tasks queued] CFS RB_ROOT: ffff880009093548 [118] PID: 2092 TASK: ffff88007d7a4760 COMMAND: "MAKEDEV" [118] PID: 1983 TASK: ffff88007e59f140 COMMAND: "udevd" [118] PID: 2064 TASK: ffff88007e40f7a0 COMMAND: "udevd" [115] PID: 2111 TASK: ffff88007e4278a0 COMMAND: "kthreadd" crash> I would think that there might be a useful address of a per-cpu structure that could be shown there as well?

And secondly, I'm confused as to why the "CFS RB_ROOT" address for all cpus is the same address -- for example, above they are both at ffff880009093548. How can the two rb trees have the same rb_root?