kernel.git/arch/powerpc/kernel/smp.c, branch linux-4.14.y

powerpc/smp: Move setup_profiling_timer() under CONFIG_PROFILING

2022-01-27T08:00:58Z

[ Upstream commit a4ac0d249a5db80e79d573db9e4ad29354b643a8 ] setup_profiling_timer() is only needed when CONFIG_PROFILING is enabled. Fixes the following W=1 warning when CONFIG_PROFILING=n: linux/arch/powerpc/kernel/smp.c:1638:5: error: no previous prototype for ‘setup_profiling_timer’ Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211124093254.1054750-5-mpe@ellerman.id.au Signed-off-by: Sasha Levin

powerpc/smp: Set numa node before updating mask

2021-05-22T08:57:37Z

[ Upstream commit 6980d13f0dd189846887bbbfa43793d9a41768d3 ] Geethika reported a trace when doing a dlpar CPU add. ------------[ cut here ]------------ WARNING: CPU: 152 PID: 1134 at kernel/sched/topology.c:2057 CPU: 152 PID: 1134 Comm: kworker/152:1 Not tainted 5.12.0-rc5-master #5 Workqueue: events cpuset_hotplug_workfn NIP: c0000000001cfc14 LR: c0000000001cfc10 CTR: c0000000007e3420 REGS: c0000034a08eb260 TRAP: 0700 Not tainted (5.12.0-rc5-master+) MSR: 8000000000029033 CR: 28828422 XER: 00000020 CFAR: c0000000001fd888 IRQMASK: 0 #012GPR00: c0000000001cfc10 c0000034a08eb500 c000000001f35400 0000000000000027 #012GPR04: c0000035abaa8010 c0000035abb30a00 0000000000000027 c0000035abaa8018 #012GPR08: 0000000000000023 c0000035abaaef48 00000035aa540000 c0000035a49dffe8 #012GPR12: 0000000028828424 c0000035bf1a1c80 0000000000000497 0000000000000004 #012GPR16: c00000000347a258 0000000000000140 c00000000203d468 c000000001a1a490 #012GPR20: c000000001f9c160 c0000034adf70920 c0000034aec9fd20 0000000100087bd3 #012GPR24: 0000000100087bd3 c0000035b3de09f8 0000000000000030 c0000035b3de09f8 #012GPR28: 0000000000000028 c00000000347a280 c0000034aefe0b00 c0000000010a2a68 NIP [c0000000001cfc14] build_sched_domains+0x6a4/0x1500 LR [c0000000001cfc10] build_sched_domains+0x6a0/0x1500 Call Trace: [c0000034a08eb500] [c0000000001cfc10] build_sched_domains+0x6a0/0x1500 (unreliable) [c0000034a08eb640] [c0000000001d1e6c] partition_sched_domains_locked+0x3ec/0x530 [c0000034a08eb6e0] [c0000000002936d4] rebuild_sched_domains_locked+0x524/0xbf0 [c0000034a08eb7e0] [c000000000296bb0] rebuild_sched_domains+0x40/0x70 [c0000034a08eb810] [c000000000296e74] cpuset_hotplug_workfn+0x294/0xe20 [c0000034a08ebc30] [c000000000178dd0] process_one_work+0x300/0x670 [c0000034a08ebd10] [c0000000001791b8] worker_thread+0x78/0x520 [c0000034a08ebda0] [c000000000185090] kthread+0x1a0/0x1b0 [c0000034a08ebe10] [c00000000000ccec] ret_from_kernel_thread+0x5c/0x70 Instruction dump: 7d2903a6 4e800421 e8410018 7f67db78 7fe6fb78 7f45d378 7f84e378 7c681b78 3c62ff1a 3863c6f8 4802dc35 60000000 <0fe00000> 3920fff4 f9210070 e86100a0 ---[ end trace 532d9066d3d4d7ec ]--- Some of the per-CPU masks use cpu_cpu_mask as a filter to limit the search for related CPUs. On a dlpar add of a CPU, update cpu_cpu_mask before updating the per-CPU masks. This will ensure the cpu_cpu_mask is updated correctly before its used in setting the masks. Setting the numa_node will ensure that when cpu_cpu_mask() gets called, the correct node number is used. This code movement helped fix the above call trace. Reported-by: Geetika Moolchandani Signed-off-by: Srikar Dronamraju Reviewed-by: Nathan Lynch Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210401154200.150077-1-srikar@linux.vnet.ibm.com Signed-off-by: Sasha Levin

powerpc/smp: Add Power9 scheduler topology

2017-08-31T08:16:08Z

In previous generations of Power processors each core had a private L2 cache. The Power 9 processor has a slightly different design where the L2 cache is shared among pairs of cores rather than being completely private. Making the scheduler aware of this cache sharing allows the scheduler to make better migration decisions. For example, if two CPU heavy tasks share a core then one task can be migrated to the paired core to improve throughput. Under the existing three level topology the task could be migrated to any core on the same chip, while with the new topology it would be preferentially migrated to the paired core so it remains cache-hot. Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman

powerpc/smp: Add cpu_l2_cache_map

2017-08-31T04:26:56Z

We want to add an extra level to the CPU scheduler topology to account for cores which share a cache. To do this we need to build a cpumask for each CPU that indicates which CPUs share this cache to use as an input to the scheduler. Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman

powerpc/smp: Rework CPU topology construction

2017-08-31T04:26:51Z

The CPU scheduler topology is constructed from a number of per-cpu cpumasks which describe which sets of logical CPUs are related in some fashion. Current code that handles constructing these masks when CPUs are hot(un)plugged can be simplified a bit by exploiting the fact that the scheduler requires higher levels of the toplogy (e.g package level groupings) to be supersets of the lower levels (e.g. threas in a core). This patch reworks the cpumask construction to be simpler and easier to extend with extra topology levels. Signed-off-by: Oliver O'Halloran [mpe: Fix CONFIG_HOTPLUG_CPU=n build] Signed-off-by: Michael Ellerman

powerpc/smp: Use cpu_to_chip_id() to find core siblings

2017-08-31T04:26:50Z

When building the CPU scheduler topology the kernel uses the ibm,chipid property from the devicetree to group logical CPUs. Currently the DT search for this property is open-coded in smp.c and this functionality is a duplication of what's in cpu_to_chip_id() already. This patch removes the existing search in favor of that. It's worth mentioning that the semantics of the search are different in cpu_to_chip_id(). When there is no ibm,chipid in the CPUs node it will also search /cpus and / for the property, but this should not effect the output topology. Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman

powerpc: NMI IPI improve lock primitive

2017-08-09T13:45:26Z

When the NMI IPI lock is contended, spin at low SMT priority, using loads only, and with interrupts enabled (where possible). This improves behaviour under high contention (e.g., a system crash when a number of CPUs are trying to enter the debugger). Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

Merge tag 'v4.13-rc1' into fixes

2017-07-31T10:20:29Z

The fixes branch is based off a random pre-rc1 commit, because we had some fixes that needed to go in before rc1 was released. However we now need to fix some code that went in after that point, but before rc1, so merge rc1 to get that code into fixes so we can fix it!

powerpc/smp: Call smp_ops->setup_cpu() directly on the boot CPU

2017-07-28T09:35:45Z

In smp_cpus_done() we need to call smp_ops->setup_cpu() for the boot CPU, which means it has to run *on* the boot CPU. In the past we ensured it ran on the boot CPU by changing the CPU affinity mask of current directly. That was removed in commit 6d11b87d55eb ("powerpc/smp: Replace open coded task affinity logic"), and replaced with a work queue call. Unfortunately using a work queue leads to a lockdep warning, now that the CPU hotplug lock is a regular semaphore: ====================================================== WARNING: possible circular locking dependency detected ... kworker/0:1/971 is trying to acquire lock: (cpu_hotplug_lock.rw_sem){++++++}, at: [] apply_workqueue_attrs+0x34/0xa0 but task is already holding lock: ((&wfc.work)){+.+.+.}, at: [] process_one_work+0x25c/0x800 ... CPU0 CPU1 ---- ---- lock((&wfc.work)); lock(cpu_hotplug_lock.rw_sem); lock((&wfc.work)); lock(cpu_hotplug_lock.rw_sem); Although the deadlock can't happen in practice, because smp_cpus_done() only runs in early boot before CPU hotplug is allowed, lockdep can't tell that. Luckily in commit 8fb12156b8db ("init: Pin init task to the boot CPU, initially") tglx changed the generic code to pin init to the boot CPU to begin with. The unpinning of init from the boot CPU happens in sched_init_smp(), which is called after smp_cpus_done(). So smp_cpus_done() is always called on the boot CPU, which means we don't need the work queue call at all - and the lockdep warning goes away. Signed-off-by: Michael Ellerman Reviewed-by: Thomas Gleixner

powerpc/64s: implement arch-specific hardlockup watchdog

2017-07-12T23:26:02Z

Implement an arch-speicfic watchdog rather than use the perf-based hardlockup detector. The new watchdog takes the soft-NMI directly, rather than going through perf. Perf interrupts are to be made maskable in future, so that would prevent the perf detector from working in those regions. Additionally, implement a SMP based detector where all CPUs watch one another by pinging a shared cpumask. This is because powerpc Book3S does not have a true periodic local NMI, but some platforms do implement a true NMI IPI. If a CPU is stuck with interrupts hard disabled, the soft-NMI watchdog does not work, but the SMP watchdog will. Even on platforms without a true NMI IPI to get a good trace from the stuck CPU, other CPUs will notice the lockup sufficiently to report it and panic. [npiggin@gmail.com: honor watchdog disable at boot/hotplug] Link: http://lkml.kernel.org/r/20170621001346.5bb337c9@roar.ozlabs.ibm.com [npiggin@gmail.com: fix false positive warning at CPU unplug] Link: http://lkml.kernel.org/r/20170630080740.20766-1-npiggin@gmail.com [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170616065715.18390-6-npiggin@gmail.com Signed-off-by: Nicholas Piggin Reviewed-by: Don Zickus Tested-by: Babu Moger [sparc] Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds