Re: [PATCH v12 0/7] Make cpuid <-> nodeid mapping persistent

[Dou Liyang]

Ping...

At 09/02/2016 02:57 PM, Dou Liyang wrote:
> Ping...
>
> At 08/25/2016 04:35 PM, Dou Liyang wrote:
> > [Summary]
> >
> > Use ACPI tables: MADT, DSDT.
> > 1. Create cpuid in order based on Local Apic ID in MADT(apicid).
> > 2. Obtain the nodeid by the proc_id in DSDT.
> > 3. Make the cpuid <-> nodeid mapping persistent.
> >
> > The mapping relations:
> >
> > proc_id in DSDT <--> Processor ID in MADT(acpiid) <--> Local Apic ID
> > in MADT(apicid)
> >         ^                                                        ^
> >         |                                                        |
> >         vâ                                                       vâ
> >    pxm in DSDT                                                 cpuid
> >         ^
> >         |
> >         v
> >      nodeid
> >
> > [Problem]
> >
> > cpuid <-> nodeid mapping is firstly established at boot time. And
> > workqueue caches
> > the mapping in wq_numa_possible_cpumask in wq_numa_init() at boot time.
> >
> > When doing node online/offline, cpuid <-> nodeid mapping is
> > established/destroyed,
> > which means, cpuid <-> nodeid mapping will change if node hotplug
> > happens. But
> > workqueue does not update wq_numa_possible_cpumask.
> >
> > So here is the problem:
> >
> > Assume we have the following cpuid <-> nodeid in the beginning:
> >
> >   Node | CPU
> > ------------------------
> > node 0 |  0-14, 60-74
> > node 1 | 15-29, 75-89
> > node 2 | 30-44, 90-104
> > node 3 | 45-59, 105-119
> >
> > and we hot-remove node2 and node3, it becomes:
> >
> >   Node | CPU
> > ------------------------
> > node 0 |  0-14, 60-74
> > node 1 | 15-29, 75-89
> >
> > and we hot-add node4 and node5, it becomes:
> >
> >   Node | CPU
> > ------------------------
> > node 0 |  0-14, 60-74
> > node 1 | 15-29, 75-89
> > node 4 | 30-59
> > node 5 | 90-119
> >
> > But in wq_numa_possible_cpumask, cpu30 is still mapped to node2, and
> > the like.
> >
> > When a pool workqueue is initialized, if its cpumask belongs to a
> > node, its
> > pool->node will be mapped to that node. And memory used by this
> > workqueue will
> > also be allocated on that node.
> >
> > static struct worker_pool *get_unbound_pool(const struct
> > workqueue_attrs *attrs){
> > ...
> >         /* if cpumask is contained inside a NUMA node, we belong to
> > that node */
> >         if (wq_numa_enabled) {
> >                 for_each_node(node) {
> >                         if (cpumask_subset(pool->attrs->cpumask,
> >
> > wq_numa_possible_cpumask[node])) {
> >                                 pool->node = node;
> >                                 break;
> >                         }
> >                 }
> >         }
> >
> > Since wq_numa_possible_cpumask is not updated, it could be mapped to
> > an offline node,
> > which will lead to memory allocation failure:
> >
> >  SLUB: Unable to allocate memory on node 2 (gfp=0x80d0)
> >   cache: kmalloc-192, object size: 192, buffer size: 192, default
> > order: 1, min order: 0
> >   node 0: slabs: 6172, objs: 259224, free: 245741
> >   node 1: slabs: 3261, objs: 136962, free: 127656
> >
> > It happens here:
> >
> > create_worker(struct worker_pool *pool)
> >  |--> worker = alloc_worker(pool->node);
> >
> > static struct worker *alloc_worker(int node)
> > {
> >         struct worker *worker;
> >
> >         worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); -->
> > Here, useing the wrong node.
> >
> >         ......
> >
> >         return worker;
> > }
> >
> >
> > [Solution]
> >
> > There are four mappings in the kernel:
> > 1. nodeid (logical node id)   <->   pxm
> > 2. apicid (physical cpu id)   <->   nodeid
> > 3. cpuid (logical cpu id)     <->   apicid
> > 4. cpuid (logical cpu id)     <->   nodeid
> >
> > 1. pxm (proximity domain) is provided by ACPI firmware in SRAT, and
> > nodeid <-> pxm
> >    mapping is setup at boot time. This mapping is persistent, won't
> > change.
> >
> > 2. apicid <-> nodeid mapping is setup using info in 1. The mapping is
> > setup at boot
> >    time and CPU hotadd time, and cleared at CPU hotremove time. This
> > mapping is also
> >    persistent.
> >
> > 3. cpuid <-> apicid mapping is setup at boot time and CPU hotadd time.
> > cpuid is
> >    allocated, lower ids first, and released at CPU hotremove time,
> > reused for other
> >    hotadded CPUs. So this mapping is not persistent.
> >
> > 4. cpuid <-> nodeid mapping is also setup at boot time and CPU hotadd
> > time, and
> >    cleared at CPU hotremove time. As a result of 3, this mapping is
> > not persistent.
> >
> > To fix this problem, we establish cpuid <-> nodeid mapping for all the
> > possible
> > cpus at boot time, and make it persistent. And according to
> > init_cpu_to_node(),
> > cpuid <-> nodeid mapping is based on apicid <-> nodeid mapping and
> > cpuid <-> apicid
> > mapping. So the key point is obtaining all cpus' apicid.
> >
> > apicid can be obtained by _MAT (Multiple APIC Table Entry) method or
> > found in
> > MADT (Multiple APIC Description Table). So we finish the job in the
> > following steps:
> >
> > 1. Enable apic registeration flow to handle both enabled and disabled
> > cpus.
> >    This is done by introducing an extra parameter to
> > generic_processor_info to let the
> >    caller control if disabled cpus are ignored.
> >
> > 2. Introduce a new array storing all possible cpuid <-> apicid
> > mapping. And also modify
> >    the way cpuid is calculated. Establish all possible cpuid <->
> > apicid mapping when
> >    registering local apic. Store the mapping in this array.
> >
> > 3. Enable _MAT and MADT relative apis to return non-presnet or
> > disabled cpus' apicid.
> >    This is also done by introducing an extra parameter to these apis
> > to let the caller
> >    control if disabled cpus are ignored.
> >
> > 4. Establish all possible cpuid <-> nodeid mapping.
> >    This is done via an additional acpi namespace walk for processors.
> >
> >
> > For previous discussion, please refer to:
> > https://lkml.org/lkml/2015/2/27/145
> > https://lkml.org/lkml/2015/3/25/989
> > https://lkml.org/lkml/2015/5/14/244
> > https://lkml.org/lkml/2015/7/7/200
> > https://lkml.org/lkml/2015/9/27/209
> > https://lkml.org/lkml/2016/5/19/212
> > https://lkml.org/lkml/2016/7/19/181
> > https://lkml.org/lkml/2016/7/25/99
> > https://lkml.org/lkml/2016/7/26/52
> > https://lkml.org/lkml/2016/8/8/96
> >
> > Change log v11 -> v12:
> > 1. Rebase
> > 2. Add a short summary
> >
> > Change log v10 -> v11:
> > 1. Reduce the number of repeat judgment of online/offline
> > 2. Seperate out the functionality in the enable or disable situation
> >
> > Change log v9 -> v10:
> > 1. Providing an empty definition of acpi_set_processor_mapping() for
> > CONFIG_ACPI_HOTPLUG_CPU unset. In patch 5.
> > 2. Fix auto build test ERROR on ia64/next. In patch 5.
> > 3. Fix some comment.
> >
> > Change log v8 -> v9:
> > 1. Providing an empty definition of acpi_set_processor_mapping() for
> > CONFIG_ACPI_HOTPLUG_CPU unset.
> >
> > Change log v7 -> v8:
> > 1. Provide the mechanism to validate processors in the ACPI tables.
> > 2. Provide the interface to validate the proc_id when setting the
> > mapping.
> >
> > Change log v6 -> v7:
> > 1. Fix arm64 build failure.
> >
> > Change log v5 -> v6:
> > 1. Define func acpi_map_cpu2node() for x86 and ia64 respectively.
> >
> > Change log v4 -> v5:
> > 1. Remove useless code in patch 1.
> > 2. Small improvement of commit message.
> >
> > Change log v3 -> v4:
> > 1. Fix the kernel panic at boot time. The cause is that I tried to
> > build zonelists
> >    before per cpu areas were initialized.
> >
> > Change log v2 -> v3:
> > 1. Online memory-less nodes at boot time to map cpus of memory-less
> > nodes.
> > 2. Build zonelists for memory-less nodes so that memory allocator will
> > fall
> >    back to proper nodes automatically.
> >
> > Change log v1 -> v2:
> > 1. Split code movement and actual changes. Add patch 1.
> > 2. Synchronize best near online node record when node hotplug happens.
> > In patch 2.
> > 3. Fix some comment.
> >
> > Dou Liyang (2):
> >   acpi: Provide the mechanism to validate processors in the ACPI tables
> >   acpi: Provide the interface to validate the proc_id
> >
> > Gu Zheng (4):
> >   x86, acpi, cpu-hotplug: Enable acpi to register all possible cpus at
> >     boot time.
> >   x86, acpi, cpu-hotplug: Introduce cpuid_to_apicid[] array to store
> >     persistent cpuid <-> apicid mapping.
> >   x86, acpi, cpu-hotplug: Enable MADT APIs to return disabled apicid.
> >   x86, acpi, cpu-hotplug: Set persistent cpuid <-> nodeid mapping when
> >     booting.
> >
> > Tang Chen (1):
> >   x86, memhp, numa: Online memory-less nodes at boot time.
> >
> >  arch/ia64/kernel/acpi.c       |   3 +-
> >  arch/x86/include/asm/mpspec.h |   1 +
> >  arch/x86/kernel/acpi/boot.c   |  11 ++--
> >  arch/x86/kernel/apic/apic.c   |  77 +++++++++++++++++++++++--
> >  arch/x86/mm/numa.c            |  27 +++++----
> >  drivers/acpi/acpi_processor.c | 105 ++++++++++++++++++++++++++++++++-
> >  drivers/acpi/bus.c            |   1 +
> >  drivers/acpi/processor_core.c | 131
> > +++++++++++++++++++++++++++++++++++-------
> >  include/linux/acpi.h          |   6 ++
> >  9 files changed, 311 insertions(+), 51 deletions(-)