----- "Michael Holzheu" <holzheu(a)linux.vnet.ibm.com&gt; wrote: > Hi Dave, > > I have a problem with a dump where I have defined five CPUs and two of > them are offline. In fact the logical CPUs are defined as follows: > > 0 on > 1 on > 2 off > 3 off > 4 on > > The CPU online map looks correct: > > crash> print/x *cpu_online_mask > $4 = { > bits = {0x13} ---> b10011 > } > > When I issue "ps" I see that all running tasks are idle, but the CPU > numbers are not correct (0,1,2 and not 0,1,4): > > PID PPID CPU TASK ST %MEM VSZ RSS COMM > > 0 0 0 800ef0 RU 0.0 0 0 [swapper] > > 0 0 1 18c24240 RU 0.0 0 0 [swapper] > > 0 0 2 18c2c340 RU 0.0 0 0 [swapper] > > I tried to debug the problem, but got stuck somewhere in "task.c". I > think there is a problem with the idle threads initialization, where the > online map is not considered. > > Maybe you can see the bug immediately. Otherwise I will have spend more > effort for debugging that problem. I hope not :-) Does "sys" show 5 or 3 cpus? I'm guessing it shows 3, but should show 5. It looks like the s390/s390x files need to use "get_highest_cpu_online()-1" (like x86_64 and ppc64) in order to determine the number of cpus to account for. As it is now, they do this, and would therefore only account for the first 3 cpus: int s390x_get_smp_cpus(void) { return get_cpus_online(); } int s390_get_smp_cpus(void) { return get_cpus_online(); }

Hallo Dave, On Fri, 2010-01-22 at 09:32 -0500, Dave Anderson wrote: > ----- "Michael Holzheu" <holzheu(a)linux.vnet.ibm.com&gt; wrote: > > > Hi Dave, > > > > I have a problem with a dump where I have defined five CPUs and two of > > them are offline. In fact the logical CPUs are defined as follows: > > > > 0 on > > 1 on > > 2 off > > 3 off > > 4 on > > > > The CPU online map looks correct: > > > > crash> print/x *cpu_online_mask > > $4 = { > > bits = {0x13} ---> b10011 > > } > > > > When I issue "ps" I see that all running tasks are idle, but the CPU > > numbers are not correct (0,1,2 and not 0,1,4): > > > > PID PPID CPU TASK ST %MEM VSZ RSS COMM > > > 0 0 0 800ef0 RU 0.0 0 0 [swapper] > > > 0 0 1 18c24240 RU 0.0 0 0 [swapper] > > > 0 0 2 18c2c340 RU 0.0 0 0 [swapper] > > > > I tried to debug the problem, but got stuck somewhere in "task.c". I > > think there is a problem with the idle threads initialization, where the > > online map is not considered. > > > > Maybe you can see the bug immediately. Otherwise I will have spend more > > effort for debugging that problem. I hope not :-) > > Does "sys" show 5 or 3 cpus? I'm guessing it shows 3, but should show 5. Yes it shows 3. > It looks like the s390/s390x files need to use "get_highest_cpu_online()-1" > (like x86_64 and ppc64) in order to determine the number of cpus to account > for. As it is now, they do this, and would therefore only account for the > first 3 cpus: > > int > s390x_get_smp_cpus(void) > { > return get_cpus_online(); > } > > int > s390_get_smp_cpus(void) > { > return get_cpus_online(); > } Hmmm ok... When I change get_smp_cpus() to return "get_highest_cpu_online() + 1" I see five swapper idle tasks when using "ps". The problem I now have is that I have to provide a backtrace for the offline cpus. But the offline CPUs do not have any stack on s390. Is there a way to tell crash that there is no backtrace available? Probably I overlooked something...