Hi Mathieu, > -----Original Message----- > From: Mathieu Desnoyers [mailto:mathieu.desnoy...@efficios.com] > Sent: Tuesday, 13 January 2015 2:06 AM > To: David OShea > Cc: lttng-dev > Subject: Re: [lttng-dev] Segfault at v_read() called from > lib_ring_buffer_try_reserve_slow() in LTTng-UST traced app - CPU/VMware > dependent [...] > > > Is it possible that this is an issue in LTTng, or should I work out > how the > > > kernel works out which CPU it is running on and then look into > whether > > > there > > > are any VMware bugs in this area? > > > > This appears to be very likely a VMware bug. /proc/cpuinfo should > show > > 4 CPUs (and sysconf(_SC_NPROCESSORS_CONF) should return 4) if the > current > > CPU number can be 0, 1, 2, 3 throughout execution.
/proc/cpuinfo shows two CPUs: processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 26 model name : Intel(R) Xeon(R) CPU X7550 @ 2.00GHz stepping : 4 microcode : 8 cpu MHz : 1995.000 cache size : 18432 KB physical id : 0 siblings : 1 core id : 0 cpu cores : 1 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 11 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts xtopology tsc_reliable nonstop_tsc aperfmperf unfair_spinlock pni ssse3 cx16 sse4_1 sse4_2 popcnt hypervisor lahf_lm ida dts bogomips : 3990.00 clflush size : 64 cache_alignment : 64 address sizes : 40 bits physical, 48 bits virtual power management: processor : 1 vendor_id : GenuineIntel cpu family : 6 model : 26 model name : Intel(R) Xeon(R) CPU X7550 @ 2.00GHz stepping : 4 microcode : 8 cpu MHz : 1995.000 cache size : 18432 KB physical id : 2 siblings : 1 core id : 0 cpu cores : 1 apicid : 2 initial apicid : 2 fpu : yes fpu_exception : yes cpuid level : 11 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts xtopology tsc_reliable nonstop_tsc aperfmperf unfair_spinlock pni ssse3 cx16 sse4_1 sse4_2 popcnt hypervisor lahf_lm ida dts bogomips : 3990.00 clflush size : 64 cache_alignment : 64 address sizes : 40 bits physical, 48 bits virtual power management: > You might want to look at the sysconf(3) manpage, especially the parts > about > _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN. My guess is that vmware > is lying > about the number of "possible" CPUs (_SC_NPROCESSORS_CONF). _SC_NPROCESSORS_CONF = 2 _SC_NPROCESSORS_ONLN = 2 Thanks for the pointers, I will look into possible VMware bugs. Out of curiosity, what happens if I happened to have a system with hot-pluggable CPUs - does _SC_NPROCESSORS_CONF reflect the maximum number of CPUs I can insert, and that is how many LTTng will support? Thanks, David ---------------------------------------------------------------------- The information contained in this transmission may be confidential. Any disclosure, copying, or further distribution of confidential information is not permitted unless such privilege is explicitly granted in writing by Quantum. Quantum reserves the right to have electronic communications, including email and attachments, sent across its networks filtered through anti virus and spam software programs and retain such messages in order to comply with applicable data security and retention requirements. Quantum is not responsible for the proper and complete transmission of the substance of this communication or for any delay in its receipt. _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
