@@ -1,6 +1,22 @@
# SPDX-License-Identifier: BSD-3-Clause
# Copyright(c) 2023 PANTHEON.tech s.r.o.
+"""CPU core representation and filtering.
+
+This module provides a unified representation of logical CPU cores along
+with filtering capabilities.
+
+When symmetric multiprocessing (SMP or multithreading) is enabled on a server,
+the physical CPU cores are split into logical CPU cores with different IDs.
+
+:class:`LogicalCoreCountFilter` filters by the number of logical cores. It's possible to specify
+the socket from which to filter the number of logical cores. It's also possible to not use all
+logical CPU cores from each physical core (e.g. only the first logical core of each physical core).
+
+:class:`LogicalCoreListFilter` filters by logical core IDs. This mostly checks that
+the logical cores are actually present on the server.
+"""
+
import dataclasses
from abc import ABC, abstractmethod
from collections.abc import Iterable, ValuesView
@@ -11,9 +27,17 @@
@dataclass(slots=True, frozen=True)
class LogicalCore(object):
- """
- Representation of a CPU core. A physical core is represented in OS
- by multiple logical cores (lcores) if CPU multithreading is enabled.
+ """Representation of a logical CPU core.
+
+ A physical core is represented in OS by multiple logical cores (lcores)
+ if CPU multithreading is enabled. When multithreading is disabled, their IDs are the same.
+
+ Attributes:
+ lcore: The logical core ID of a CPU core. It's the same as `core` with
+ disabled multithreading.
+ core: The physical core ID of a CPU core.
+ socket: The physical socket ID where the CPU resides.
+ node: The NUMA node ID where the CPU resides.
"""
lcore: int
@@ -22,27 +46,36 @@ class LogicalCore(object):
node: int
def __int__(self) -> int:
+ """The CPU is best represented by the logical core, as that's what we configure in EAL."""
return self.lcore
class LogicalCoreList(object):
- """
- Convert these options into a list of logical core ids.
- lcore_list=[LogicalCore1, LogicalCore2] - a list of LogicalCores
- lcore_list=[0,1,2,3] - a list of int indices
- lcore_list=['0','1','2-3'] - a list of str indices; ranges are supported
- lcore_list='0,1,2-3' - a comma delimited str of indices; ranges are supported
-
- The class creates a unified format used across the framework and allows
- the user to use either a str representation (using str(instance) or directly
- in f-strings) or a list representation (by accessing instance.lcore_list).
- Empty lcore_list is allowed.
+ r"""A unified way to store :class:`LogicalCore`\s.
+
+ Create a unified format used across the framework and allow the user to use
+ either a :class:`str` representation (using ``str(instance)`` or directly in f-strings)
+ or a :class:`list` representation (by accessing the `lcore_list` property,
+ which stores logical core IDs).
"""
_lcore_list: list[int]
_lcore_str: str
def __init__(self, lcore_list: list[int] | list[str] | list[LogicalCore] | str):
+ """Process `lcore_list`, then sort.
+
+ There are four supported logical core list formats::
+
+ lcore_list=[LogicalCore1, LogicalCore2] # a list of LogicalCores
+ lcore_list=[0,1,2,3] # a list of int indices
+ lcore_list=['0','1','2-3'] # a list of str indices; ranges are supported
+ lcore_list='0,1,2-3' # a comma delimited str of indices; ranges are supported
+
+ Args:
+ lcore_list: Various ways to represent multiple logical cores.
+ Empty `lcore_list` is allowed.
+ """
self._lcore_list = []
if isinstance(lcore_list, str):
lcore_list = lcore_list.split(",")
@@ -58,6 +91,7 @@ def __init__(self, lcore_list: list[int] | list[str] | list[LogicalCore] | str):
@property
def lcore_list(self) -> list[int]:
+ """The logical core IDs."""
return self._lcore_list
def _get_consecutive_lcores_range(self, lcore_ids_list: list[int]) -> list[str]:
@@ -83,28 +117,30 @@ def _get_consecutive_lcores_range(self, lcore_ids_list: list[int]) -> list[str]:
return formatted_core_list
def __str__(self) -> str:
+ """The consecutive ranges of logical core IDs."""
return self._lcore_str
@dataclasses.dataclass(slots=True, frozen=True)
class LogicalCoreCount(object):
- """
- Define the number of logical cores to use.
- If sockets is not None, socket_count is ignored.
- """
+ """Define the number of logical cores per physical cores per sockets."""
+ #: Use this many logical cores per each physical core.
lcores_per_core: int = 1
+ #: Use this many physical cores per each socket.
cores_per_socket: int = 2
+ #: Use this many sockets.
socket_count: int = 1
+ #: Use exactly these sockets. This takes precedence over `socket_count`,
+ #: so when `sockets` is not :data:`None`, `socket_count` is ignored.
sockets: list[int] | None = None
class LogicalCoreFilter(ABC):
- """
- Filter according to the input filter specifier. Each filter needs to be
- implemented in a derived class.
- This class only implements operations common to all filters, such as sorting
- the list to be filtered beforehand.
+ """Common filtering class.
+
+ Each filter needs to be implemented in a subclass. This base class sorts the list of cores
+ and defines the filtering method, which must be implemented by subclasses.
"""
_filter_specifier: LogicalCoreCount | LogicalCoreList
@@ -116,6 +152,17 @@ def __init__(
filter_specifier: LogicalCoreCount | LogicalCoreList,
ascending: bool = True,
):
+ """Filter according to the input filter specifier.
+
+ The input `lcore_list` is copied and sorted by physical core before filtering.
+ The list is copied so that the original is left intact.
+
+ Args:
+ lcore_list: The logical CPU cores to filter.
+ filter_specifier: Filter cores from `lcore_list` according to this filter.
+ ascending: Sort cores in ascending order (lowest to highest IDs). If data:`False`,
+ sort in descending order.
+ """
self._filter_specifier = filter_specifier
# sorting by core is needed in case hyperthreading is enabled
@@ -124,31 +171,45 @@ def __init__(
@abstractmethod
def filter(self) -> list[LogicalCore]:
- """
- Use self._filter_specifier to filter self._lcores_to_filter
- and return the list of filtered LogicalCores.
- self._lcores_to_filter is a sorted copy of the original list,
- so it may be modified.
+ r"""Filter the cores.
+
+ Use `self._filter_specifier` to filter `self._lcores_to_filter` and return
+ the filtered :class:`LogicalCore`\s.
+ `self._lcores_to_filter` is a sorted copy of the original list, so it may be modified.
+
+ Returns:
+ The filtered cores.
"""
class LogicalCoreCountFilter(LogicalCoreFilter):
- """
+ """Filter cores by specified counts.
+
Filter the input list of LogicalCores according to specified rules:
- Use cores from the specified number of sockets or from the specified socket ids.
- If sockets is specified, it takes precedence over socket_count.
- From each of those sockets, use only cores_per_socket of cores.
- And for each core, use lcores_per_core of logical cores. Hypertheading
- must be enabled for this to take effect.
- If ascending is True, use cores with the lowest numerical id first
- and continue in ascending order. If False, start with the highest
- id and continue in descending order. This ordering affects which
- sockets to consider first as well.
+
+ * The input `filter_specifier` is :class:`LogicalCoreCount`,
+ * Use cores from the specified number of sockets or from the specified socket ids,
+ * If `sockets` is specified, it takes precedence over `socket_count`,
+ * From each of those sockets, use only `cores_per_socket` of cores,
+ * And for each core, use `lcores_per_core` of logical cores. Hypertheading
+ must be enabled for this to take effect.
"""
_filter_specifier: LogicalCoreCount
def filter(self) -> list[LogicalCore]:
+ """Filter the cores according to :class:`LogicalCoreCount`.
+
+ Start by filtering the allowed sockets. The cores matching the allowed sockets are returned.
+ The cores of each socket are stored in separate lists.
+
+ Then filter the allowed physical cores from those lists of cores per socket. When filtering
+ physical cores, store the desired number of logical cores per physical core which then
+ together constitute the final filtered list.
+
+ Returns:
+ The filtered cores.
+ """
sockets_to_filter = self._filter_sockets(self._lcores_to_filter)
filtered_lcores = []
for socket_to_filter in sockets_to_filter:
@@ -158,24 +219,37 @@ def filter(self) -> list[LogicalCore]:
def _filter_sockets(
self, lcores_to_filter: Iterable[LogicalCore]
) -> ValuesView[list[LogicalCore]]:
- """
- Remove all lcores that don't match the specified socket(s).
- If self._filter_specifier.sockets is not None, keep lcores from those sockets,
- otherwise keep lcores from the first
- self._filter_specifier.socket_count sockets.
+ """Filter a list of cores per each allowed socket.
+
+ The sockets may be specified in two ways, either a number or a specific list of sockets.
+ In case of a specific list, we just need to return the cores from those sockets.
+ If filtering a number of cores, we need to go through all cores and note which sockets
+ appear and only filter from the first n that appear.
+
+ Args:
+ lcores_to_filter: The cores to filter. These must be sorted by the physical core.
+
+ Returns:
+ A list of lists of logical CPU cores. Each list contains cores from one socket.
"""
allowed_sockets: set[int] = set()
socket_count = self._filter_specifier.socket_count
if self._filter_specifier.sockets:
+ # when sockets in filter is specified, the sockets are already set
socket_count = len(self._filter_specifier.sockets)
allowed_sockets = set(self._filter_specifier.sockets)
+ # filter socket_count sockets from all sockets by checking the socket of each CPU
filtered_lcores: dict[int, list[LogicalCore]] = {}
for lcore in lcores_to_filter:
if not self._filter_specifier.sockets:
+ # this is when sockets is not set, so we do the actual filtering
+ # when it is set, allowed_sockets is already defined and can't be changed
if len(allowed_sockets) < socket_count:
+ # allowed_sockets is a set, so adding an existing socket won't re-add it
allowed_sockets.add(lcore.socket)
if lcore.socket in allowed_sockets:
+ # separate lcores into sockets; this makes it easier in further processing
if lcore.socket in filtered_lcores:
filtered_lcores[lcore.socket].append(lcore)
else:
@@ -192,12 +266,13 @@ def _filter_sockets(
def _filter_cores_from_socket(
self, lcores_to_filter: Iterable[LogicalCore]
) -> list[LogicalCore]:
- """
- Keep only the first self._filter_specifier.cores_per_socket cores.
- In multithreaded environments, keep only
- the first self._filter_specifier.lcores_per_core lcores of those cores.
- """
+ """Filter a list of cores from the given socket.
+
+ Go through the cores and note how many logical cores per physical core have been filtered.
+ Returns:
+ The filtered logical CPU cores.
+ """
# no need to use ordered dict, from Python3.7 the dict
# insertion order is preserved (LIFO).
lcore_count_per_core_map: dict[int, int] = {}
@@ -238,15 +313,21 @@ def _filter_cores_from_socket(
class LogicalCoreListFilter(LogicalCoreFilter):
- """
- Filter the input list of Logical Cores according to the input list of
- lcore indices.
- An empty LogicalCoreList won't filter anything.
+ """Filter the logical CPU cores by logical CPU core IDs.
+
+ This is a simple filter that looks at logical CPU IDs and only filter those that match.
+
+ The input filter is :class:`LogicalCoreList`. An empty LogicalCoreList won't filter anything.
"""
_filter_specifier: LogicalCoreList
def filter(self) -> list[LogicalCore]:
+ """Filter based on logical CPU core ID.
+
+ Return:
+ The filtered logical CPU cores.
+ """
if not len(self._filter_specifier.lcore_list):
return self._lcores_to_filter
@@ -269,6 +350,17 @@ def lcore_filter(
filter_specifier: LogicalCoreCount | LogicalCoreList,
ascending: bool,
) -> LogicalCoreFilter:
+ """Factory for providing the filter that corresponds to `filter_specifier`.
+
+ Args:
+ core_list: The logical CPU cores to filter.
+ filter_specifier: The filter to use.
+ ascending: Sort cores in ascending order (lowest to highest IDs). If :data:`False`,
+ sort in descending order.
+
+ Returns:
+ The filter that corresponds to `filter_specifier`.
+ """
if isinstance(filter_specifier, LogicalCoreList):
return LogicalCoreListFilter(core_list, filter_specifier, ascending)
elif isinstance(filter_specifier, LogicalCoreCount):