kernel.git/arch/powerpc/kernel/smp.c, branch linux-2.6.19.y

IRQ: Maintain regs pointer globally rather than passing to IRQ handlers

2006-10-05T14:10:12Z

Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)

[POWERPC] Fix non-MPIC CHRPs with CONFIG_SMP set

2006-07-25T15:27:04Z

Pseudo-CHRP machines like Pegasos without an MPIC would crash at boot if CONFIG_SMP was set because the "smp_ops" pointer was set to MPIC related ops unconditionally. This patch makes it NULL on machines that don't support SMP and provides proper default behaviour in the callers when smp_ops is NULL. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Paul Mackerras

Remove obsolete #include

2006-06-30T17:25:36Z

Signed-off-by: Jörn Engel Signed-off-by: Adrian Bunk

[POWERPC] Add starting of secondary 86xx CPUs.

2006-06-21T05:01:28Z

Clear the high BATS during load_up_mmu if FTR_HAS_HIGH_BATS. Allow just a bit more time for secondary CPUs to phone home. Signed-off-by: Wei Zhang Signed-off-by: Haiying Wang Signed-off-by: Jon Loeliger Signed-off-by: Paul Mackerras

[PATCH] for_each_possible_cpu: powerpc

2006-03-29T02:44:15Z

for_each_cpu() actually iterates across all possible CPUs. We've had mistakes in the past where people were using for_each_cpu() where they should have been iterating across only online or present CPUs. This is inefficient and possibly buggy. We're renaming for_each_cpu() to for_each_possible_cpu() to avoid this in the future. This patch replaces for_each_cpu with for_each_possible_cpu. Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Paul Mackerras

powerpc: Implement accurate task and CPU time accounting

2006-02-24T03:05:56Z

This implements accurate task and cpu time accounting for 64-bit powerpc kernels. Instead of accounting a whole jiffy of time to a task on a timer interrupt because that task happened to be running at the time, we now account time in units of timebase ticks according to the actual time spent by the task in user mode and kernel mode. We also count the time spent processing hardware and software interrupts accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If that is not set, we do tick-based approximate accounting as before. To get this accurate information, we read either the PURR (processor utilization of resources register) on POWER5 machines, or the timebase on other machines on * each entry to the kernel from usermode * each exit to usermode * transitions between process context, hard irq context and soft irq context in kernel mode * context switches. On POWER5 systems with shared-processor logical partitioning we also read both the PURR and the timebase at each timer interrupt and context switch in order to determine how much time has been taken by the hypervisor to run other partitions ("steal" time). Unfortunately, since we need values of the PURR on both threads at the same time to accurately calculate the steal time, and since we can only calculate steal time on a per-core basis, the apportioning of the steal time between idle time (time which we ceded to the hypervisor in the idle loop) and actual stolen time is somewhat approximate at the moment. This is all based quite heavily on what s390 does, and it uses the generic interfaces that were added by the s390 developers, i.e. account_system_time(), account_user_time(), etc. This patch doesn't add any new interfaces between the kernel and userspace, and doesn't change the units in which time is reported to userspace by things such as /proc/stat, /proc//stat, getrusage(), times(), etc. Internally the various task and cpu times are stored in timebase units, but they are converted to USER_HZ units (1/100th of a second) when reported to userspace. Some precision is therefore lost but there should not be any accumulating error, since the internal accumulation is at full precision. Signed-off-by: Paul Mackerras

[PATCH] powerpc: avoid timer interrupt replay effect when onlining cpu

2006-02-07T10:51:54Z

When a cpu is hotplug-onlined, if we don't set per_cpu(last_jiffy) to something sane, timer_interrupt will execute its while loop for every tick missed since the cpu was last online (or since the system was booted, if we're adding a new cpu). This can cause weird hangs, ssh sessions dropping, and we can even go xmon if we take a global IPI at the wrong time. Signed-off-by: Nathan Lynch Signed-off-by: Paul Mackerras

[PATCH] powerpc: task_thread_info()

2006-01-12T17:08:57Z

Signed-off-by: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] ppc64: Add NUMA cpu summary at boot

2006-01-09T03:53:37Z

We used to print a NUMA cpu summary at boot before the hotplug cpu code was added. This has been useful for catching machine configuration as well as firmware bugs in the past. This patch restores that functionality. An example of the output is: Node 0 CPUs: 0-7 Node 1 CPUs: 8-15 Signed-off-by: Anton Blanchard Signed-off-by: Paul Mackerras

[PATCH] powerpc: Add arch dependent basic infrastructure for Kdump.

2006-01-09T03:52:28Z

Implementing the machine_crash_shutdown which will be called by crash_kexec (called in case of a panic, sysrq etc.). Disable the interrupts, shootdown cpus using debugger IPI and collect regs for all CPUs. elfcorehdr= specifies the location of elf core header stored by the crashed kernel. This command line option will be passed by the kexec-tools to capture kernel. savemaxmem= specifies the actual memory size that the first kernel has and this value will be used for dumping in the capture kernel. This command line option will be passed by the kexec-tools to capture kernel. Signed-off-by: Haren Myneni Signed-off-by: Michael Ellerman Signed-off-by: Paul Mackerras