From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ... --- Documentation/scheduler/sched-domains.rst | 81 +++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 Documentation/scheduler/sched-domains.rst (limited to 'Documentation/scheduler/sched-domains.rst') diff --git a/Documentation/scheduler/sched-domains.rst b/Documentation/scheduler/sched-domains.rst new file mode 100644 index 000000000..e57ad2830 --- /dev/null +++ b/Documentation/scheduler/sched-domains.rst @@ -0,0 +1,81 @@ +================= +Scheduler Domains +================= + +Each CPU has a "base" scheduling domain (struct sched_domain). The domain +hierarchy is built from these base domains via the ->parent pointer. ->parent +MUST be NULL terminated, and domain structures should be per-CPU as they are +locklessly updated. + +Each scheduling domain spans a number of CPUs (stored in the ->span field). +A domain's span MUST be a superset of it child's span (this restriction could +be relaxed if the need arises), and a base domain for CPU i MUST span at least +i. The top domain for each CPU will generally span all CPUs in the system +although strictly it doesn't have to, but this could lead to a case where some +CPUs will never be given tasks to run unless the CPUs allowed mask is +explicitly set. A sched domain's span means "balance process load among these +CPUs". + +Each scheduling domain must have one or more CPU groups (struct sched_group) +which are organised as a circular one way linked list from the ->groups +pointer. The union of cpumasks of these groups MUST be the same as the +domain's span. The group pointed to by the ->groups pointer MUST contain the CPU +to which the domain belongs. Groups may be shared among CPUs as they contain +read only data after they have been set up. The intersection of cpumasks from +any two of these groups may be non empty. If this is the case the SD_OVERLAP +flag is set on the corresponding scheduling domain and its groups may not be +shared between CPUs. + +Balancing within a sched domain occurs between groups. That is, each group +is treated as one entity. The load of a group is defined as the sum of the +load of each of its member CPUs, and only when the load of a group becomes +out of balance are tasks moved between groups. + +In kernel/sched/core.c, trigger_load_balance() is run periodically on each CPU +through scheduler_tick(). It raises a softirq after the next regularly scheduled +rebalancing event for the current runqueue has arrived. The actual load +balancing workhorse, run_rebalance_domains()->rebalance_domains(), is then run +in softirq context (SCHED_SOFTIRQ). + +The latter function takes two arguments: the runqueue of current CPU and whether +the CPU was idle at the time the scheduler_tick() happened and iterates over all +sched domains our CPU is on, starting from its base domain and going up the ->parent +chain. While doing that, it checks to see if the current domain has exhausted its +rebalance interval. If so, it runs load_balance() on that domain. It then checks +the parent sched_domain (if it exists), and the parent of the parent and so +forth. + +Initially, load_balance() finds the busiest group in the current sched domain. +If it succeeds, it looks for the busiest runqueue of all the CPUs' runqueues in +that group. If it manages to find such a runqueue, it locks both our initial +CPU's runqueue and the newly found busiest one and starts moving tasks from it +to our runqueue. The exact number of tasks amounts to an imbalance previously +computed while iterating over this sched domain's groups. + +Implementing sched domains +========================== + +The "base" domain will "span" the first level of the hierarchy. In the case +of SMT, you'll span all siblings of the physical CPU, with each group being +a single virtual CPU. + +In SMP, the parent of the base domain will span all physical CPUs in the +node. Each group being a single physical CPU. Then with NUMA, the parent +of the SMP domain will span the entire machine, with each group having the +cpumask of a node. Or, you could do multi-level NUMA or Opteron, for example, +might have just one domain covering its one NUMA level. + +The implementor should read comments in include/linux/sched/sd_flags.h: +SD_* to get an idea of the specifics and what to tune for the SD flags +of a sched_domain. + +Architectures may override the generic domain builder and the default SD flags +for a given topology level by creating a sched_domain_topology_level array and +calling set_sched_topology() with this array as the parameter. + +The sched-domains debugging infrastructure can be enabled by enabling +CONFIG_SCHED_DEBUG and adding 'sched_verbose' to your cmdline. If you +forgot to tweak your cmdline, you can also flip the +/sys/kernel/debug/sched/verbose knob. This enables an error checking parse of +the sched domains which should catch most possible errors (described above). It +also prints out the domain structure in a visual format. -- cgit v1.2.3