Re: [Crash-utility] [PATCH] Display online cpus value in preference to kt->cpus

Howdy, crash 5.0.0 introduced a change to ppc64_paca_init() in ppc64.c to manipulate kt->cpus to fix a 4.0-8.11 regression when cpu_possible_map has more cpus than cpu_online_map. The change basically adjusts kt->cpus to the highest cpu index + 1. In situations where cpus from 0 through highest index are all online, this will equal online cpus. On IBM POWER based system supporting SMT, we can have it dynamically enabled and disabled and so we can go from: brucelp3:~ # ppc64_cpu --smt=on brucelp3:~ # cat /sys/devices/system/cpu/online 0-9 to brucelp3:~ # ppc64_cpu --smt=off brucelp3:~ # cat /sys/devices/system/cpu/online 0,2,4,6,8 In this situation, the new code will determine that kt->cpus is 9. crash will display: KERNEL: /boot/vmlinux DUMPFILE: /dev/mem CPUS: 9 ===============> Rather than 5 DATE: Fri Feb 26 06:06:51 2010 UPTIME: 04:22:34 LOAD AVERAGE: 0.49, 0.14, 0.05 TASKS: 320 NODENAME: brucelp3 RELEASE: 2.6.32.8-0.3-ppc64 VERSION: #1 SMP 2010-02-22 16:22:25 +0100 MACHINE: ppc64 (unknown Mhz) MEMORY: 1 GB PID: 19948 COMMAND: "crash" TASK: c00000002433be50 [THREAD_INFO: c0000000238a0000] CPU: 2 STATE: TASK_RUNNING (ACTIVE) kernel_init() initially does come up with 5 for kt->cpus initially before the machdep init routine (ppc64_paca_init) ends up changing it to 9 in the above situation. Because of the way other parts of the code seem to iterate, allowing kt->cpus to get set to the number of online cpus (5) would make them not work properly either. Case in point, the ps command. It would iterate through the first 5 cpus for the swapper tasks and stop, providing no information for swapper tasks on online cpus 6 and 8. Rather than displaying kt->cpu for cpu count to display to users, can we call get_cpus_online() itself. This will solve the problem of keeping kt->cpu separate from get_cpus_online(). So commands like ps, set etc can still rely on kt->cpu as set for each architecture. Additionally, we need to consider providing the value as it exists after machine dependent init in case the symbols required by get_cpus_online() are not available. The patch provided creates a new routine called get_cpus_to_display() in kernel.c that simply attempts to retrieve the count of online CPUs with get_cpus_online(). However, since the cpu_online_map symbol may not be available with all kernels, the cpus_to_display() routine will return the value for kt->cpus if get_cpus_online() return 0 for that case to maintain backwards compatibility. With this in mind, all locations (mainly the display_machine_stats() routines for each architecture, display_sys_stats() and dump_kernel_table()) in the source that would print the cpu count using kt->cpus now call get_cpus_to_display() to obtain that value. This should hopefully provide the user with an expected CPU count regardless of the internal manipulation that is sometimes done to the kt->cpus value. regards, -- Luciano Chavez <lnx1138(a)linux.vnet.ibm.com&gt; IBM Linux Technology Center

diff -up crash-5.0.1/alpha.c.orig crash-5.0.1/alpha.c --- crash-5.0.1/alpha.c.orig 2010-03-04 07:19:23.000000000 -0600 +++ crash-5.0.1/alpha.c 2010-03-04 07:20:43.000000000 -0600 @@ -2641,7 +2641,7 @@ alpha_display_machine_stats(void) fprintf(fp, " MACHINE TYPE: %s\n", uts->machine); fprintf(fp, " MEMORY SIZE: %s\n", get_memory_size(buf)); - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); fprintf(fp, " PROCESSOR SPEED: "); if ((mhz = machdep->processor_speed())) fprintf(fp, "%ld Mhz\n", mhz); diff -up crash-5.0.1/defs.h.orig crash-5.0.1/defs.h --- crash-5.0.1/defs.h.orig 2010-02-17 15:21:24.000000000 -0600 +++ crash-5.0.1/defs.h 2010-03-04 07:20:43.000000000 -0600 @@ -3717,6 +3717,7 @@ int get_cpus_online(void); int get_cpus_present(void); int get_cpus_possible(void); int get_highest_cpu_online(void); +int get_cpus_to_display(void); int in_cpu_map(int, int); void paravirt_init(void); void print_stack_text_syms(struct bt_info *, ulong, ulong); diff -up crash-5.0.1/ia64.c.orig crash-5.0.1/ia64.c --- crash-5.0.1/ia64.c.orig 2010-02-17 15:21:24.000000000 -0600 +++ crash-5.0.1/ia64.c 2010-03-04 07:20:43.000000000 -0600 @@ -2325,7 +2325,7 @@ ia64_display_machine_stats(void) fprintf(fp, " MACHINE TYPE: %s\n", uts->machine); fprintf(fp, " MEMORY SIZE: %s\n", get_memory_size(buf)); - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); fprintf(fp, " PROCESSOR SPEED: "); if ((mhz = machdep->processor_speed())) fprintf(fp, "%ld Mhz\n", mhz); diff -up crash-5.0.1/kernel.c.orig crash-5.0.1/kernel.c --- crash-5.0.1/kernel.c.orig 2010-02-17 15:21:24.000000000 -0600 +++ crash-5.0.1/kernel.c 2010-03-04 07:20:43.000000000 -0600 @@ -3871,7 +3871,7 @@ display_sys_stats(void) } - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); if (ACTIVE()) get_symbol_data("xtime", sizeof(struct timespec), &kt->date); fprintf(fp, " DATE: %s\n", @@ -4289,7 +4289,7 @@ dump_kernel_table(int verbose) fprintf(fp, " init_begin: %lx\n", kt->init_begin); fprintf(fp, " init_end: %lx\n", kt->init_end); fprintf(fp, " end: %lx\n", kt->end); - fprintf(fp, " cpus: %d\n", kt->cpus); + fprintf(fp, " cpus: %d\n", get_cpus_to_display()); fprintf(fp, " cpus_override: %s\n", kt->cpus_override); fprintf(fp, " NR_CPUS: %d (compiled-in to this version of %s)\n", NR_CPUS, pc->program_name); @@ -6257,6 +6257,16 @@ get_cpus_possible() } /* + * For when displaying cpus, return the number of cpus online if possible, otherwise kt->cpus. + */ +int +get_cpus_to_display(void) +{ + int online = get_cpus_online(); + return (online ? online : kt->cpus); +} + +/* * Xen machine-address to pseudo-physical-page translator. */ ulonglong diff -up crash-5.0.1/ppc64.c.orig crash-5.0.1/ppc64.c --- crash-5.0.1/ppc64.c.orig 2010-02-17 15:21:24.000000000 -0600 +++ crash-5.0.1/ppc64.c 2010-03-04 07:20:43.000000000 -0600 @@ -2215,7 +2215,7 @@ ppc64_display_machine_stats(void) fprintf(fp, " MACHINE TYPE: %s\n", uts->machine); fprintf(fp, " MEMORY SIZE: %s\n", get_memory_size(buf)); - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); fprintf(fp, " PROCESSOR SPEED: "); if ((mhz = machdep->processor_speed())) fprintf(fp, "%ld Mhz\n", mhz); diff -up crash-5.0.1/ppc.c.orig crash-5.0.1/ppc.c --- crash-5.0.1/ppc.c.orig 2010-03-04 07:20:14.000000000 -0600 +++ crash-5.0.1/ppc.c 2010-03-04 07:20:43.000000000 -0600 @@ -1355,7 +1355,7 @@ ppc_display_machine_stats(void) fprintf(fp, " MACHINE TYPE: %s\n", uts->machine); fprintf(fp, " MEMORY SIZE: %s\n", get_memory_size(buf)); - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); fprintf(fp, " PROCESSOR SPEED: "); if ((mhz = machdep->processor_speed())) fprintf(fp, "%ld Mhz\n", mhz); diff -up crash-5.0.1/s390.c.orig crash-5.0.1/s390.c --- crash-5.0.1/s390.c.orig 2010-02-17 15:21:24.000000000 -0600 +++ crash-5.0.1/s390.c 2010-03-04 07:20:43.000000000 -0600 @@ -1032,7 +1032,7 @@ s390_display_machine_stats(void) fprintf(fp, " MACHINE TYPE: %s\n", uts->machine); fprintf(fp, " MEMORY SIZE: %s\n", get_memory_size(buf)); - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); fprintf(fp, " PROCESSOR SPEED: "); if ((mhz = machdep->processor_speed())) fprintf(fp, "%ld Mhz\n", mhz); diff -up crash-5.0.1/s390x.c.orig crash-5.0.1/s390x.c --- crash-5.0.1/s390x.c.orig 2010-02-17 15:21:24.000000000 -0600 +++ crash-5.0.1/s390x.c 2010-03-04 07:20:43.000000000 -0600 @@ -1284,7 +1284,7 @@ s390x_display_machine_stats(void) fprintf(fp, " MACHINE TYPE: %s\n", uts->machine); fprintf(fp, " MEMORY SIZE: %s\n", get_memory_size(buf)); - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); fprintf(fp, " PROCESSOR SPEED: "); if ((mhz = machdep->processor_speed())) fprintf(fp, "%ld Mhz\n", mhz); diff -up crash-5.0.1/x86_64.c.orig crash-5.0.1/x86_64.c --- crash-5.0.1/x86_64.c.orig 2010-02-17 15:21:24.000000000 -0600 +++ crash-5.0.1/x86_64.c 2010-03-04 07:20:43.000000000 -0600 @@ -4412,7 +4412,7 @@ x86_64_display_machine_stats(void) fprintf(fp, " MACHINE TYPE: %s\n", uts->machine); fprintf(fp, " MEMORY SIZE: %s\n", get_memory_size(buf)); - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); fprintf(fp, " PROCESSOR SPEED: "); if ((mhz = machdep->processor_speed())) fprintf(fp, "%ld Mhz\n", mhz); diff -up crash-5.0.1/x86.c.orig crash-5.0.1/x86.c --- crash-5.0.1/x86.c.orig 2010-02-17 15:21:24.000000000 -0600 +++ crash-5.0.1/x86.c 2010-03-04 07:20:43.000000000 -0600 @@ -3950,7 +3950,7 @@ x86_display_machine_stats(void) fprintf(fp, " MACHINE TYPE: %s\n", uts->machine); fprintf(fp, " MEMORY SIZE: %s\n", get_memory_size(buf)); - fprintf(fp, " CPUS: %d\n", kt->cpus); + fprintf(fp, " CPUS: %d\n", get_cpus_to_display()); fprintf(fp, " PROCESSOR SPEED: "); if ((mhz = machdep->processor_speed())) fprintf(fp, "%ld Mhz\n", mhz); -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility