kernel.git/arch/powerpc/kernel/smp.c, branch linux-2.6.37.y

powerpc: Account time using timebase rather than PURR

2010-09-02T04:07:31Z

Currently, when CONFIG_VIRT_CPU_ACCOUNTING is enabled, we use the PURR register for measuring the user and system time used by processes, as well as other related times such as hardirq and softirq times. This turns out to be quite confusing for users because it means that a program will often be measured as taking less time when run on a multi-threaded processor (SMT2 or SMT4 mode) than it does when run on a single-threaded processor (ST mode), even though the program takes longer to finish. The discrepancy is accounted for as stolen time, which is also confusing, particularly when there are no other partitions running. This changes the accounting to use the timebase instead, meaning that the reported user and system times are the actual number of real-time seconds that the program was executing on the processor thread, regardless of which SMT mode the processor is in. Thus a program will generally show greater user and system times when run on a multi-threaded processor than on a single-threaded processor. On pSeries systems on POWER5 or later processors, we measure the stolen time (time when this partition wasn't running) using the hypervisor dispatch trace log. We check for new entries in the log on every entry from user mode and on every transition from kernel process context to soft or hard IRQ context (i.e. when account_system_vtime() gets called). So that we can correctly distinguish time stolen from user time and time stolen from system time, without having to check the log on every exit to user mode, we store separate timestamps for exit to user mode and entry from user mode. On systems that have a SPURR (POWER6 and POWER7), we read the SPURR in account_system_vtime() (as before), and then apportion the SPURR ticks since the last time we read it between scaled user time and scaled system time according to the relative proportions of user time and system time over the same interval. This avoids having to read the SPURR on every kernel entry and exit. On systems that have PURR but not SPURR (i.e., POWER5), we do the same using the PURR rather than the SPURR. This disables the DTL user interface in /sys/debug/kernel/powerpc/dtl for now since it conflicts with the use of the dispatch trace log by the time accounting code. Signed-off-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt

powerpc: Move arch_sd_sibling_asym_packing() to smp.c

2010-09-02T04:07:31Z

Simple cleanup by moving arch_sd_sibling_asym_packing from process.c to smp.c to save an #ifdef CONFIG_SMP No functionality change. Signed-off-by: Michael Neuling Signed-off-by: Benjamin Herrenschmidt

powerpc: Silence __cpu_up() under normal operation

2010-08-24T05:26:29Z

During CPU offline/online tests __cpu_up would flood the logs with the following message: Processor 0 found. This provides no useful information to the user as there is no context provided, and since the operation was a success (to this point) it is expected that the CPU will come back online, providing all the feedback necessary. Change the "Processor found" message to DBG() similar to other such messages in the same function. Also, add an appropriate log level for the "Processor is stuck" message. Signed-off-by: Darren Hart Acked-by: Will Schmidt Cc: Thomas Gleixner Cc: Nathan Fontenot Cc: Robert Jennings Cc: Brian King Signed-off-by: Benjamin Herrenschmidt

powerpc/smp: remove the incorrect decrementer initial codes for AP

2010-07-31T04:56:31Z

We already defined start_cpu_decrementer() to invoke decrementer for AP as the following path: start_secondary() -> secondary_cpu_time_init() -> start_cpu_decrementer() So remove these incorrect codes introduced from commit: e7f75ad0 powerpc/47x: Base ppc476 support And actually we really should not enable decrementer before calling set_dec(). Signed-off-by: Tiejun Chen Signed-off-by: Benjamin Herrenschmidt

powerpc: Clean up obsolete code relating to decrementer and timebase

2010-07-09T01:26:16Z

Since the decrementer and timekeeping code was moved over to using the generic clockevents and timekeeping infrastructure, several variables and functions have been obsolete and effectively unused. This deletes them. In particular, wakeup_decrementer() is no longer needed since the generic code reprograms the decrementer as part of the process of resuming the timekeeping code, which happens during sysdev resume. Thus the wakeup_decrementer calls in the suspend_enter methods for 52xx platforms have been removed. The call in the powermac cpu frequency change code has been replaced by set_dec(1), which will cause a timer interrupt as soon as interrupts are enabled, and the generic code will then reprogram the decrementer with the correct value. This also simplifies the generic_suspend_en/disable_irqs functions and makes them static since they are not referenced outside time.c. The preempt_enable/disable calls are removed because the generic code has disabled all but the boot cpu at the point where these functions are called, so we can't be moved to another cpu. Signed-off-by: Paul Mackerras Signed-off-by: Benjamin Herrenschmidt

powerpc: Use common cpu_die (fixes SMP+SUSPEND build)

2010-05-21T07:31:08Z

Configuring a powerpc 32 bit kernel for both SMP and SUSPEND turns on CPU_HOTPLUG to enable disable_nonboot_cpus to be called by the common suspend code. Previously the definition of cpu_die for ppc32 was in the powermac platform code, causing it to be undefined if that platform as not selected. arch/powerpc/kernel/built-in.o: In function 'cpu_idle': arch/powerpc/kernel/idle.c:98: undefined reference to 'cpu_die' Move the code from setup_64 to smp.c and rename the power mac versions to their specific names. Note that this does not setup the cpu_die pointers in either smp_ops (request a given cpu die) or ppc_md (make this cpu die), for other platforms but there are generic versions in smp.c. Reported-by: Matt Sealey Reported-by: Kumar Gala Signed-off-by: Milton Miller Signed-off-by: Anton Vorontsov Signed-off-by: Benjamin Herrenschmidt

powerpc/cpumask: Update some comments

2010-05-06T07:41:59Z

Since the *_map cpumask variants are deprecated, change the comments to instead refer to *_mask. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt

powerpc/cpumask: Dynamically allocate cpu_sibling_map and cpu_core_map cpumasks

2010-05-06T07:41:56Z

Dynamically allocate cpu_sibling_map and cpu_core_map cpumasks. We don't need to set_cpu_online() the boot cpu in smp_prepare_boot_cpu, init/main.c does it for us. We also postpone setting of the boot cpu in cpu_sibling_map and cpu_core_map until when the memory allocator is available (smp_prepare_cpus), similar to x86. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt

powerpc/cpumask: Convert fixup_irqs to new cpumask API

2010-05-06T07:16:14Z

Use new cpumask_* functions, and dynamically allocate cpumask in fixup_irqs. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt

powerpc/cpumask: Convert smp_cpus_done to new cpumask API

2010-05-06T07:16:13Z

Use the new cpumask_* functions and dynamically allocate the cpumask in smp_cpus_done. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt