On Tue, 7 Dec 2010, shaohui.zheng@xxxxxxxxx wrote: > From: Shaohui Zheng <shaohui.zheng@xxxxxxxxx> > > CPU physical hot-add/hot-remove are supported on some hardwares, and it > was already supported in current linux kernel. NUMA Hotplug Emulator provides > a mechanism to emulate the process with software method. It can be used for > testing or debuging purpose. > > CPU physical hotplug is different with logical CPU online/offline. Logical > online/offline is controled by interface /sys/device/cpu/cpuX/online. CPU > hotplug emulator uses probe/release interface. It becomes possible to do cpu > hotplug automation and stress > > Add cpu interface probe/release under sysfs for x86_64. User can use this > interface to emulate the cpu hot-add and hot-remove process. > > Directive: > *) Reserve CPU thru grub parameter like: > maxcpus=4 > > the rest CPUs will not be initiliazed. > > *) Probe CPU > we can use the probe interface to hot-add new CPUs: > echo nid > /sys/devices/system/cpu/probe > > *) Release a CPU > echo cpu > /sys/devices/system/cpu/release > > A reserved CPU will be hot-added to the specified node. > 1) nid == 0, the CPU will be added to the real node which the CPU > should be in > 2) nid != 0, add the CPU to node nid even through it is a fake node. > This patch is undoubtedly going to conflict with Tejun's unification of the 32 and 64 bit NUMA boot paths, specifically the patch at http://marc.info/?l=linux-kernel&m=129087151912379. Tejun, what's the status of that patchset posted on November 27? Any comments about this change? > CC: Ingo Molnar <mingo@xxxxxxx> > CC: Len Brown <len.brown@xxxxxxxxx> > CC: Yinghai Lu <Yinghai.Lu@xxxxxxx> > Signed-off-by: Shaohui Zheng <shaohui.zheng@xxxxxxxxx> > Signed-off-by: Haicheng Li <haicheng.li@xxxxxxxxx> > --- > Index: linux-hpe4/arch/x86/kernel/acpi/boot.c > =================================================================== > --- linux-hpe4.orig/arch/x86/kernel/acpi/boot.c 2010-11-26 09:24:40.287725018 +0800 > +++ linux-hpe4/arch/x86/kernel/acpi/boot.c 2010-11-26 09:24:53.277724996 +0800 > @@ -647,8 +647,44 @@ > } > EXPORT_SYMBOL(acpi_map_lsapic); > > +#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE > +static void acpi_map_cpu2node_emu(int cpu, int physid, int nid) > +{ > +#ifdef CONFIG_ACPI_NUMA > +#ifdef CONFIG_X86_64 > + apicid_to_node[physid] = nid; > + numa_set_node(cpu, nid); > +#else /* CONFIG_X86_32 */ > + apicid_2_node[physid] = nid; > + cpu_to_node_map[cpu] = nid; > +#endif > +#endif > +} > + > +static u16 cpu_to_apicid_saved[CONFIG_NR_CPUS]; > +int __ref acpi_map_lsapic_emu(int pcpu, int nid) > +{ > + /* backup cpu apicid to array cpu_to_apicid_saved */ > + if (cpu_to_apicid_saved[pcpu] == 0 && > + per_cpu(x86_cpu_to_apicid, pcpu) != BAD_APICID) > + cpu_to_apicid_saved[pcpu] = per_cpu(x86_cpu_to_apicid, pcpu); > + > + per_cpu(x86_cpu_to_apicid, pcpu) = cpu_to_apicid_saved[pcpu]; > + acpi_map_cpu2node_emu(pcpu, per_cpu(x86_cpu_to_apicid, pcpu), nid); > + > + return pcpu; > +} > +EXPORT_SYMBOL(acpi_map_lsapic_emu); > +#endif > + > int acpi_unmap_lsapic(int cpu) > { > +#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE > + /* backup cpu apicid to array cpu_to_apicid_saved */ > + if (cpu_to_apicid_saved[cpu] == 0 && > + per_cpu(x86_cpu_to_apicid, cpu) != BAD_APICID) > + cpu_to_apicid_saved[cpu] = per_cpu(x86_cpu_to_apicid, cpu); > +#endif > per_cpu(x86_cpu_to_apicid, cpu) = -1; > set_cpu_present(cpu, false); > num_processors--; > Index: linux-hpe4/arch/x86/kernel/smpboot.c > =================================================================== > --- linux-hpe4.orig/arch/x86/kernel/smpboot.c 2010-11-26 09:24:40.297724969 +0800 > +++ linux-hpe4/arch/x86/kernel/smpboot.c 2010-11-26 12:48:58.977725001 +0800 > @@ -107,8 +107,6 @@ > mutex_unlock(&x86_cpu_hotplug_driver_mutex); > } > > -ssize_t arch_cpu_probe(const char *buf, size_t count) { return -1; } > -ssize_t arch_cpu_release(const char *buf, size_t count) { return -1; } > #else > static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ; > #define get_idle_for_cpu(x) (idle_thread_array[(x)]) > Index: linux-hpe4/arch/x86/kernel/topology.c > =================================================================== > --- linux-hpe4.orig/arch/x86/kernel/topology.c 2010-11-26 09:24:52.477725000 +0800 > +++ linux-hpe4/arch/x86/kernel/topology.c 2010-11-26 12:48:58.987725001 +0800 > @@ -30,6 +30,9 @@ > #include <linux/init.h> > #include <linux/smp.h> > #include <asm/cpu.h> > +#include <linux/cpu.h> > +#include <linux/topology.h> > +#include <linux/acpi.h> > > static DEFINE_PER_CPU(struct x86_cpu, cpu_devices); > > @@ -66,6 +69,74 @@ > unregister_cpu(&per_cpu(cpu_devices, num).cpu); > } > EXPORT_SYMBOL(arch_unregister_cpu); > + > +ssize_t arch_cpu_probe(const char *buf, size_t count) > +{ > + int nid = 0; > + int num = 0, selected = 0; > + > + /* check parameters */ > + if (!buf || count < 2) > + return -EPERM; > + > + nid = simple_strtoul(buf, NULL, 0); > + printk(KERN_DEBUG "Add a cpu to node : %d\n", nid); > + > + if (nid < 0 || nid > nr_node_ids - 1) { > + printk(KERN_ERR "Invalid NUMA node id: %d (0 <= nid < %d).\n", > + nid, nr_node_ids); > + return -EPERM; > + } > + > + if (!node_online(nid)) { > + printk(KERN_ERR "NUMA node %d is not online, give up.\n", nid); > + return -EPERM; > + } > + > + /* find first uninitialized cpu */ > + for_each_present_cpu(num) { > + if (per_cpu(cpu_sys_devices, num) == NULL) { > + selected = num; > + break; > + } > + } > + > + if (selected >= num_possible_cpus()) { > + printk(KERN_ERR "No free cpu, give up cpu probing.\n"); > + return -EPERM; > + } > + > + /* register cpu */ > + arch_register_cpu_node(selected, nid); > + acpi_map_lsapic_emu(selected, nid); > + > + return count; > +} > +EXPORT_SYMBOL(arch_cpu_probe); > + > +ssize_t arch_cpu_release(const char *buf, size_t count) > +{ > + int cpu = 0; > + > + cpu = simple_strtoul(buf, NULL, 0); > + /* cpu 0 is not hotplugable */ > + if (cpu == 0) { > + printk(KERN_ERR "can not release cpu 0.\n"); > + return -EPERM; > + } > + > + if (cpu_online(cpu)) { > + printk(KERN_DEBUG "offline cpu %d.\n", cpu); > + cpu_down(cpu); > + } > + > + arch_unregister_cpu(cpu); > + acpi_unmap_lsapic(cpu); > + > + return count; > +} > +EXPORT_SYMBOL(arch_cpu_release); > + > #else /* CONFIG_HOTPLUG_CPU */ > > static int __init arch_register_cpu(int num) > @@ -83,8 +154,14 @@ > register_one_node(i); > #endif > > - for_each_present_cpu(i) > - arch_register_cpu(i); > + /* > + * when cpu hotplug emulation enabled, register the online cpu only, > + * the rests are reserved for cpu probe. > + */ > + for_each_present_cpu(i) { > + if ((cpu_hpe_on && cpu_online(i)) || !cpu_hpe_on) > + arch_register_cpu(i); > + } > > return 0; > } > Index: linux-hpe4/arch/x86/mm/numa_64.c > =================================================================== > --- linux-hpe4.orig/arch/x86/mm/numa_64.c 2010-11-26 09:24:40.317724965 +0800 > +++ linux-hpe4/arch/x86/mm/numa_64.c 2010-11-26 09:24:53.297725001 +0800 > @@ -12,6 +12,7 @@ > #include <linux/module.h> > #include <linux/nodemask.h> > #include <linux/sched.h> > +#include <linux/cpu.h> > > #include <asm/e820.h> > #include <asm/proto.h> > @@ -785,6 +786,19 @@ > } > #endif > > +#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE > +static __init int cpu_hpe_setup(char *opt) > +{ > + if (!opt) > + return -EINVAL; > + > + if (!strncmp(opt, "on", 2) || !strncmp(opt, "1", 1)) > + cpu_hpe_on = 1; > + > + return 0; > +} > +early_param("cpu_hpe", cpu_hpe_setup); > +#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ > > void __cpuinit numa_set_node(int cpu, int node) > { > Index: linux-hpe4/drivers/acpi/processor_driver.c > =================================================================== > --- linux-hpe4.orig/drivers/acpi/processor_driver.c 2010-11-26 09:24:40.327725004 +0800 > +++ linux-hpe4/drivers/acpi/processor_driver.c 2010-11-26 09:24:53.297725001 +0800 > @@ -530,6 +530,14 @@ > goto err_free_cpumask; > > sysdev = get_cpu_sysdev(pr->id); > + /* > + * Reserve cpu for hotplug emulation, the reserved cpu can be hot-added > + * throu the cpu probe interface. Return directly. > + */ > + if (sysdev == NULL) { > + goto out; > + } > + > if (sysfs_create_link(&device->dev.kobj, &sysdev->kobj, "sysdev")) { > result = -EFAULT; > goto err_remove_fs; > @@ -570,6 +578,7 @@ > goto err_remove_sysfs; > } > > +out: > return 0; > > err_remove_sysfs: > Index: linux-hpe4/drivers/base/cpu.c > =================================================================== > --- linux-hpe4.orig/drivers/base/cpu.c 2010-11-26 09:24:52.477725000 +0800 > +++ linux-hpe4/drivers/base/cpu.c 2010-11-26 09:24:53.297725001 +0800 > @@ -22,9 +22,15 @@ > }; > EXPORT_SYMBOL(cpu_sysdev_class); > > -static DEFINE_PER_CPU(struct sys_device *, cpu_sys_devices); > +DEFINE_PER_CPU(struct sys_device *, cpu_sys_devices); > > #ifdef CONFIG_HOTPLUG_CPU > +/* > + * cpu_hpe_on is a switch to enable/disable cpu hotplug emulation. it is > + * disabled in default, we can enable it throu grub parameter cpu_hpe=on > + */ > +int cpu_hpe_on; > + > static ssize_t show_online(struct sys_device *dev, struct sysdev_attribute *attr, > char *buf) > { > Index: linux-hpe4/include/linux/acpi.h > =================================================================== > --- linux-hpe4.orig/include/linux/acpi.h 2010-11-26 09:24:40.347725041 +0800 > +++ linux-hpe4/include/linux/acpi.h 2010-11-26 09:24:53.297725001 +0800 > @@ -102,6 +102,7 @@ > #ifdef CONFIG_ACPI_HOTPLUG_CPU > /* Arch dependent functions for cpu hotplug support */ > int acpi_map_lsapic(acpi_handle handle, int *pcpu); > +int acpi_map_lsapic_emu(int pcpu, int nid); > int acpi_unmap_lsapic(int cpu); > #endif /* CONFIG_ACPI_HOTPLUG_CPU */ > > Index: linux-hpe4/include/linux/cpu.h > =================================================================== > --- linux-hpe4.orig/include/linux/cpu.h 2010-11-26 09:24:52.477725000 +0800 > +++ linux-hpe4/include/linux/cpu.h 2010-11-26 09:24:53.297725001 +0800 > @@ -30,6 +30,8 @@ > struct sys_device sysdev; > }; > > +DECLARE_PER_CPU(struct sys_device *, cpu_sys_devices); > + > extern int register_cpu_node(struct cpu *cpu, int num, int nid); > > static inline int register_cpu(struct cpu *cpu, int num) > @@ -149,6 +151,7 @@ > #define register_hotcpu_notifier(nb) register_cpu_notifier(nb) > #define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb) > int cpu_down(unsigned int cpu); > +extern int cpu_hpe_on; > > #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE > extern void cpu_hotplug_driver_lock(void); > @@ -171,6 +174,7 @@ > /* These aren't inline functions due to a GCC bug. */ > #define register_hotcpu_notifier(nb) ({ (void)(nb); 0; }) > #define unregister_hotcpu_notifier(nb) ({ (void)(nb); }) > +static int cpu_hpe_on; > #endif /* CONFIG_HOTPLUG_CPU */ > > #ifdef CONFIG_PM_SLEEP_SMP > Index: linux-hpe4/Documentation/x86/x86_64/boot-options.txt > =================================================================== > --- linux-hpe4.orig/Documentation/x86/x86_64/boot-options.txt 2010-11-26 12:49:44.847725099 +0800 > +++ linux-hpe4/Documentation/x86/x86_64/boot-options.txt 2010-11-26 12:55:50.527724999 +0800 > @@ -316,3 +316,9 @@ > Do not use GB pages for kernel direct mappings. > gbpages > Use GB pages for kernel direct mappings. > + cpu_hpe=on/off > + Enable/disable CPU hotplug emulation with software method. When cpu_hpe=on, > + sysfs provides probe/release interface to hot add/remove CPUs dynamically. > + We can use maxcpus=<N> to reserve CPUs. > + This option is disabled by default. > + > > -- > Thanks & Regards, > Shaohui > > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>