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https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
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Add three more affinity scopes - WQ_AFFN_CPU, SMT and CACHE - and make CACHE the default. The code changes to actually add the additional scopes are trivial. Also add module parameter "workqueue.default_affinity_scope" to override the default scope and "affinity_scope" sysfs file to configure it per workqueue. wq_dump.py and documentations are updated accordingly. This enables significant flexibility in configuring how unbound workqueues behave. If affinity scope is set to "cpu", it'll behave close to a per-cpu workqueue. On the other hand, "system" removes all locality boundaries. Many modern machines have multiple L3 caches often while being mostly uniform in terms of memory access. Thus, workqueue's previous behavior of spreading work items in each NUMA node had negative performance implications from unncessarily crossing L3 boundaries between issue and execution. However, picking a finer grained affinity scope also has a downside in that an issuer in one group can't utilize CPUs in other groups. While dependent on the specifics of workload, there's usually a noticeable penalty in crossing L3 boundaries, so let's default to CACHE. This issue will be further addressed and documented with examples in future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
170 lines
5.3 KiB
Python
170 lines
5.3 KiB
Python
#!/usr/bin/env drgn
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#
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# Copyright (C) 2023 Tejun Heo <tj@kernel.org>
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# Copyright (C) 2023 Meta Platforms, Inc. and affiliates.
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desc = """
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This is a drgn script to show the current workqueue configuration. For more
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info on drgn, visit https://github.com/osandov/drgn.
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Affinity Scopes
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===============
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Shows the CPUs that can be used for unbound workqueues and how they will be
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grouped by each available affinity type. For each type:
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nr_pods number of CPU pods in the affinity type
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pod_cpus CPUs in each pod
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pod_node NUMA node for memory allocation for each pod
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cpu_pod pod that each CPU is associated to
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Worker Pools
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============
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Lists all worker pools indexed by their ID. For each pool:
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ref number of pool_workqueue's associated with this pool
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nice nice value of the worker threads in the pool
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idle number of idle workers
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workers number of all workers
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cpu CPU the pool is associated with (per-cpu pool)
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cpus CPUs the workers in the pool can run on (unbound pool)
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Workqueue CPU -> pool
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=====================
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Lists all workqueues along with their type and worker pool association. For
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each workqueue:
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NAME TYPE POOL_ID...
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NAME name of the workqueue
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TYPE percpu, unbound or ordered
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POOL_ID worker pool ID associated with each possible CPU
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"""
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import sys
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import drgn
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from drgn.helpers.linux.list import list_for_each_entry,list_empty
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from drgn.helpers.linux.percpu import per_cpu_ptr
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from drgn.helpers.linux.cpumask import for_each_cpu,for_each_possible_cpu
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from drgn.helpers.linux.idr import idr_for_each
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import argparse
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parser = argparse.ArgumentParser(description=desc,
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formatter_class=argparse.RawTextHelpFormatter)
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args = parser.parse_args()
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def err(s):
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print(s, file=sys.stderr, flush=True)
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sys.exit(1)
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def cpumask_str(cpumask):
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output = ""
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base = 0
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v = 0
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for cpu in for_each_cpu(cpumask[0]):
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while cpu - base >= 32:
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output += f'{hex(v)} '
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base += 32
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v = 0
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v |= 1 << (cpu - base)
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if v > 0:
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output += f'{v:08x}'
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return output.strip()
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worker_pool_idr = prog['worker_pool_idr']
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workqueues = prog['workqueues']
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wq_unbound_cpumask = prog['wq_unbound_cpumask']
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wq_pod_types = prog['wq_pod_types']
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wq_affn_dfl = prog['wq_affn_dfl']
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wq_affn_names = prog['wq_affn_names']
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WQ_UNBOUND = prog['WQ_UNBOUND']
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WQ_ORDERED = prog['__WQ_ORDERED']
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WQ_MEM_RECLAIM = prog['WQ_MEM_RECLAIM']
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WQ_AFFN_CPU = prog['WQ_AFFN_CPU']
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WQ_AFFN_SMT = prog['WQ_AFFN_SMT']
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WQ_AFFN_CACHE = prog['WQ_AFFN_CACHE']
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WQ_AFFN_NUMA = prog['WQ_AFFN_NUMA']
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WQ_AFFN_SYSTEM = prog['WQ_AFFN_SYSTEM']
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print('Affinity Scopes')
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print('===============')
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print(f'wq_unbound_cpumask={cpumask_str(wq_unbound_cpumask)}')
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def print_pod_type(pt):
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print(f' nr_pods {pt.nr_pods.value_()}')
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print(' pod_cpus', end='')
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for pod in range(pt.nr_pods):
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print(f' [{pod}]={cpumask_str(pt.pod_cpus[pod])}', end='')
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print('')
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print(' pod_node', end='')
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for pod in range(pt.nr_pods):
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print(f' [{pod}]={pt.pod_node[pod].value_()}', end='')
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print('')
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print(f' cpu_pod ', end='')
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for cpu in for_each_possible_cpu(prog):
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print(f' [{cpu}]={pt.cpu_pod[cpu].value_()}', end='')
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print('')
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for affn in [WQ_AFFN_CPU, WQ_AFFN_SMT, WQ_AFFN_CACHE, WQ_AFFN_NUMA, WQ_AFFN_SYSTEM]:
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print('')
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print(f'{wq_affn_names[affn].string_().decode().upper()}{" (default)" if affn == wq_affn_dfl else ""}')
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print_pod_type(wq_pod_types[affn])
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print('')
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print('Worker Pools')
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print('============')
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max_pool_id_len = 0
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max_ref_len = 0
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for pi, pool in idr_for_each(worker_pool_idr):
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pool = drgn.Object(prog, 'struct worker_pool', address=pool)
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max_pool_id_len = max(max_pool_id_len, len(f'{pi}'))
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max_ref_len = max(max_ref_len, len(f'{pool.refcnt.value_()}'))
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for pi, pool in idr_for_each(worker_pool_idr):
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pool = drgn.Object(prog, 'struct worker_pool', address=pool)
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print(f'pool[{pi:0{max_pool_id_len}}] ref={pool.refcnt.value_():{max_ref_len}} nice={pool.attrs.nice.value_():3} ', end='')
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print(f'idle/workers={pool.nr_idle.value_():3}/{pool.nr_workers.value_():3} ', end='')
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if pool.cpu >= 0:
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print(f'cpu={pool.cpu.value_():3}', end='')
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else:
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print(f'cpus={cpumask_str(pool.attrs.cpumask)}', end='')
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print('')
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print('')
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print('Workqueue CPU -> pool')
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print('=====================')
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print('[ workqueue \ CPU ', end='')
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for cpu in for_each_possible_cpu(prog):
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print(f' {cpu:{max_pool_id_len}}', end='')
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print(' dfl]')
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for wq in list_for_each_entry('struct workqueue_struct', workqueues.address_of_(), 'list'):
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print(f'{wq.name.string_().decode()[-24:]:24}', end='')
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if wq.flags & WQ_UNBOUND:
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if wq.flags & WQ_ORDERED:
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print(' ordered', end='')
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else:
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print(' unbound', end='')
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else:
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print(' percpu ', end='')
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for cpu in for_each_possible_cpu(prog):
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pool_id = per_cpu_ptr(wq.cpu_pwq, cpu)[0].pool.id.value_()
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field_len = max(len(str(cpu)), max_pool_id_len)
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print(f' {pool_id:{field_len}}', end='')
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if wq.flags & WQ_UNBOUND:
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print(f' {wq.dfl_pwq.pool.id.value_():{max_pool_id_len}}', end='')
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print('')
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