Use the new sample_flags to indicate whether the raw data field is
filled by the PMU driver. Although it could check with the NULL,
follow the same rule with other fields.
Remove the raw field from the perf_sample_data_init() to minimize
the number of cache lines touched.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220921220032.2858517-2-namhyung@kernel.org
While auditing 6b959ba22d ("perf/core: Fix reentry problem in
perf_output_read_group()") a few spots were found that wanted
assertions.
Notable for_each_sibling_event() relies on exclusion from
modification. This would normally be holding either ctx->lock or
ctx->mutex, however due to how things are constructed disabling IRQs
is a valid and sufficient substitute for ctx->lock.
Another possible site to add assertions would be the various
pmu::{add,del,read,..}() methods, but that's not trivially expressable
in C -- the best option is wrappers, but those are easy enough to
forget.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Besides the branch type filtering requests, 'event.attr.branch_sample_type'
also contains various flags indicating which additional information should
be captured, along with the base branch record. These flags help configure
the underlying hardware, and capture the branch records appropriately when
required e.g after PMU interrupt. But first, this moves an existing helper
perf_sample_save_hw_index() into the header before adding some more helpers
for other branch sample filter flags.
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220906084414.396220-1-anshuman.khandual@arm.com
On some platforms, some data e.g., timestamps, can be retrieved from
the PMU driver. Usually, the data from the PMU driver is more accurate.
The current perf kernel should output the PMU-filled sample data if
it's available.
To check the availability of the PMU-filled sample data, the current
perf kernel initializes the related fields in the
perf_sample_data_init(). When outputting a sample, the perf checks
whether the field is updated by the PMU driver. If yes, the updated
value will be output. If not, the perf uses an SW way to calculate the
value or just outputs the initialized value if an SW way is unavailable
either.
With more and more data being provided by the PMU driver, more fields
has to be initialized in the perf_sample_data_init(). That will
increase the number of cache lines touched in perf_sample_data_init()
and be harmful to the performance.
Add new "sample_flags" to indicate the PMU-filled sample data. The PMU
driver should set the corresponding PERF_SAMPLE_ flag when the field is
updated. The initialization of the corresponding field is not required
anymore. The following patches will make use of it and remove the
corresponding fields from the perf_sample_data_init(), which will
further minimize the number of cache lines touched.
Only clear the sample flags that have already been done by the PMU
driver in the perf_prepare_sample() for the PERF_RECORD_SAMPLE. For the
other PERF_RECORD_ event type, the sample data is not available.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220901130959.1285717-2-kan.liang@linux.intel.com
On a machine with 256 CPUs, running the recently added perf breakpoint
benchmark results in:
| $> perf bench -r 30 breakpoint thread -b 4 -p 64 -t 64
| # Running 'breakpoint/thread' benchmark:
| # Created/joined 30 threads with 4 breakpoints and 64 parallelism
| Total time: 236.418 [sec]
|
| 123134.794271 usecs/op
| 7880626.833333 usecs/op/cpu
The benchmark tests inherited breakpoint perf events across many
threads.
Looking at a perf profile, we can see that the majority of the time is
spent in various hw_breakpoint.c functions, which execute within the
'nr_bp_mutex' critical sections which then results in contention on that
mutex as well:
37.27% [kernel] [k] osq_lock
34.92% [kernel] [k] mutex_spin_on_owner
12.15% [kernel] [k] toggle_bp_slot
11.90% [kernel] [k] __reserve_bp_slot
The culprit here is task_bp_pinned(), which has a runtime complexity of
O(#tasks) due to storing all task breakpoints in the same list and
iterating through that list looking for a matching task. Clearly, this
does not scale to thousands of tasks.
Instead, make use of the "rhashtable" variant "rhltable" which stores
multiple items with the same key in a list. This results in average
runtime complexity of O(1) for task_bp_pinned().
With the optimization, the benchmark shows:
| $> perf bench -r 30 breakpoint thread -b 4 -p 64 -t 64
| # Running 'breakpoint/thread' benchmark:
| # Created/joined 30 threads with 4 breakpoints and 64 parallelism
| Total time: 0.208 [sec]
|
| 108.422396 usecs/op
| 6939.033333 usecs/op/cpu
On this particular setup that's a speedup of ~1135x.
While one option would be to make task_struct a breakpoint list node,
this would only further bloat task_struct for infrequently used data.
Furthermore, after all optimizations in this series, there's no evidence
it would result in better performance: later optimizations make the time
spent looking up entries in the hash table negligible (we'll reach the
theoretical ideal performance i.e. no constraints).
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20220829124719.675715-5-elver@google.com
Add a new "spec" bitfield to branch entries for providing speculation
information. This will be populated using hints provided by branch sampling
features on supported hardware. The following cases are covered:
* No branch speculation information is available
* Branch is speculative but taken on the wrong path
* Branch is non-speculative but taken on the correct path
* Branch is speculative and taken on the correct path
Suggested-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/834088c302faf21c7b665031dd111f424e509a64.1660211399.git.sandipan.das@amd.com
Sometimes we want to know an accurate number of samples even if it's
lost. Currenlty PERF_RECORD_LOST is generated for a ring-buffer which
might be shared with other events. So it's hard to know per-event
lost count.
Add event->lost_samples field and PERF_FORMAT_LOST to retrieve it from
userspace.
Original-patch-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220616180623.1358843-1-namhyung@kernel.org
Add an optional callback needed by some PMU features, e.g., AMD
BRS, to give a chance to the perf_events code to change its state before
a CPU goes to low power and after it comes back.
The callback is void when the PERF_NEEDS_LOPWR_CB flag is not set.
This flag must be set in arch specific perf_event.h header whenever needed.
When not set, there is no impact on the ACPI code.
Signed-off-by: Stephane Eranian <eranian@google.com>
[peterz: build fix]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220322221517.2510440-9-eranian@google.com
Commit 0793a61d4d ("performance counters: core code") added the perf
subsystem (then called Performance Counters) to Linux, creating the struct
perf_cpu_context. The comment for the struct referred to it as a "struct
perf_counter_cpu_context".
Commit cdd6c482c9 ("perf: Do the big rename: Performance Counters ->
Performance Events") changed the comment to refer to a "struct
perf_event_cpu_context", which was still the wrong name for the struct.
Change the comment to say "struct perf_cpu_context".
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220127161759.53553-3-alexandru.elisei@arm.com
Time readers that cannot take locks (due to NMI etc..) currently make
use of perf_event::shadow_ctx_time, which, for that event gives:
time' = now + (time - timestamp)
or, alternatively arranged:
time' = time + (now - timestamp)
IOW, the progression of time since the last time the shadow_ctx_time
was updated.
There's problems with this:
A) the shadow_ctx_time is per-event, even though the ctx_time it
reflects is obviously per context. The direct concequence of this
is that the context needs to iterate all events all the time to
keep the shadow_ctx_time in sync.
B) even with the prior point, the context itself might not be active
meaning its time should not advance to begin with.
C) shadow_ctx_time isn't consistently updated when ctx_time is
There are 3 users of this stuff, that suffer differently from this:
- calc_timer_values()
- perf_output_read()
- perf_event_update_userpage() /* A */
- perf_event_read_local() /* A,B */
In particular, perf_output_read() doesn't suffer at all, because it's
sample driven and hence only relevant when the event is actually
running.
This same was supposed to be true for perf_event_update_userpage(),
after all self-monitoring implies the context is active *HOWEVER*, as
per commit f792565326 ("perf/core: fix userpage->time_enabled of
inactive events") this goes wrong when combined with counter
overcommit, in that case those events that do not get scheduled when
the context becomes active (task events typically) miss out on the
EVENT_TIME update and ENABLED time is inflated (for a little while)
with the time the context was inactive. Once the event gets rotated
in, this gets corrected, leading to a non-monotonic timeflow.
perf_event_read_local() made things even worse, it can request time at
any point, suffering all the problems perf_event_update_userpage()
does and more. Because while perf_event_update_userpage() is limited
by the context being active, perf_event_read_local() users have no
such constraint.
Therefore, completely overhaul things and do away with
perf_event::shadow_ctx_time. Instead have regular context time updates
keep track of this offset directly and provide perf_event_time_now()
to complement perf_event_time().
perf_event_time_now() will, in adition to being context wide, also
take into account if the context is active. For inactive context, it
will not advance time.
This latter property means the cgroup perf_cgroup_info context needs
to grow addition state to track this.
Additionally, since all this is strictly per-cpu, we can use barrier()
to order context activity vs context time.
Fixes: 7d9285e82d ("perf/bpf: Extend the perf_event_read_local() interface, a.k.a. "bpf: perf event change needed for subsequent bpf helpers"")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Song Liu <song@kernel.org>
Tested-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/r/YcB06DasOBtU0b00@hirez.programming.kicks-ass.net
Pull perf updates from Borislav Petkov:
"Cleanup of the perf/kvm interaction."
* tag 'perf_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Drop guest callback (un)register stubs
KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c
KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y
KVM: arm64: Convert to the generic perf callbacks
KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c
KVM: Move x86's perf guest info callbacks to generic KVM
KVM: x86: More precisely identify NMI from guest when handling PMI
KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable
perf/core: Use static_call to optimize perf_guest_info_callbacks
perf: Force architectures to opt-in to guest callbacks
perf: Add wrappers for invoking guest callbacks
perf/core: Rework guest callbacks to prepare for static_call support
perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv
perf: Stop pretending that perf can handle multiple guest callbacks
KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest
KVM: x86: Register perf callbacks after calling vendor's hardware_setup()
perf: Protect perf_guest_cbs with RCU
Pull networking updates from Jakub Kicinski:
"Core
----
- Defer freeing TCP skbs to the BH handler, whenever possible, or at
least perform the freeing outside of the socket lock section to
decrease cross-CPU allocator work and improve latency.
- Add netdevice refcount tracking to locate sources of netdevice and
net namespace refcount leaks.
- Make Tx watchdog less intrusive - avoid pausing Tx and restarting
all queues from a single CPU removing latency spikes.
- Various small optimizations throughout the stack from Eric Dumazet.
- Make netdev->dev_addr[] constant, force modifications to go via
appropriate helpers to allow us to keep addresses in ordered data
structures.
- Replace unix_table_lock with per-hash locks, improving performance
of bind() calls.
- Extend skb drop tracepoint with a drop reason.
- Allow SO_MARK and SO_PRIORITY setsockopt under CAP_NET_RAW.
BPF
---
- New helpers:
- bpf_find_vma(), find and inspect VMAs for profiling use cases
- bpf_loop(), runtime-bounded loop helper trading some execution
time for much faster (if at all converging) verification
- bpf_strncmp(), improve performance, avoid compiler flakiness
- bpf_get_func_arg(), bpf_get_func_ret(), bpf_get_func_arg_cnt()
for tracing programs, all inlined by the verifier
- Support BPF relocations (CO-RE) in the kernel loader.
- Further the support for BTF_TYPE_TAG annotations.
- Allow access to local storage in sleepable helpers.
- Convert verifier argument types to a composable form with different
attributes which can be shared across types (ro, maybe-null).
- Prepare libbpf for upcoming v1.0 release by cleaning up APIs,
creating new, extensible ones where missing and deprecating those
to be removed.
Protocols
---------
- WiFi (mac80211/cfg80211):
- notify user space about long "come back in N" AP responses,
allow it to react to such temporary rejections
- allow non-standard VHT MCS 10/11 rates
- use coarse time in airtime fairness code to save CPU cycles
- Bluetooth:
- rework of HCI command execution serialization to use a common
queue and work struct, and improve handling errors reported in
the middle of a batch of commands
- rework HCI event handling to use skb_pull_data, avoiding packet
parsing pitfalls
- support AOSP Bluetooth Quality Report
- SMC:
- support net namespaces, following the RDMA model
- improve connection establishment latency by pre-clearing buffers
- introduce TCP ULP for automatic redirection to SMC
- Multi-Path TCP:
- support ioctls: SIOCINQ, OUTQ, and OUTQNSD
- support socket options: IP_TOS, IP_FREEBIND, IP_TRANSPARENT,
IPV6_FREEBIND, and IPV6_TRANSPARENT, TCP_CORK and TCP_NODELAY
- support cmsgs: TCP_INQ
- improvements in the data scheduler (assigning data to subflows)
- support fastclose option (quick shutdown of the full MPTCP
connection, similar to TCP RST in regular TCP)
- MCTP (Management Component Transport) over serial, as defined by
DMTF spec DSP0253 - "MCTP Serial Transport Binding".
Driver API
----------
- Support timestamping on bond interfaces in active/passive mode.
- Introduce generic phylink link mode validation for drivers which
don't have any quirks and where MAC capability bits fully express
what's supported. Allow PCS layer to participate in the validation.
Convert a number of drivers.
- Add support to set/get size of buffers on the Rx rings and size of
the tx copybreak buffer via ethtool.
- Support offloading TC actions as first-class citizens rather than
only as attributes of filters, improve sharing and device resource
utilization.
- WiFi (mac80211/cfg80211):
- support forwarding offload (ndo_fill_forward_path)
- support for background radar detection hardware
- SA Query Procedures offload on the AP side
New hardware / drivers
----------------------
- tsnep - FPGA based TSN endpoint Ethernet MAC used in PLCs with
real-time requirements for isochronous communication with protocols
like OPC UA Pub/Sub.
- Qualcomm BAM-DMUX WWAN - driver for data channels of modems
integrated into many older Qualcomm SoCs, e.g. MSM8916 or MSM8974
(qcom_bam_dmux).
- Microchip LAN966x multi-port Gigabit AVB/TSN Ethernet Switch driver
with support for bridging, VLANs and multicast forwarding
(lan966x).
- iwlmei driver for co-operating between Intel's WiFi driver and
Intel's Active Management Technology (AMT) devices.
- mse102x - Vertexcom MSE102x Homeplug GreenPHY chips
- Bluetooth:
- MediaTek MT7921 SDIO devices
- Foxconn MT7922A
- Realtek RTL8852AE
Drivers
-------
- Significantly improve performance in the datapaths of: lan78xx,
ax88179_178a, lantiq_xrx200, bnxt.
- Intel Ethernet NICs:
- igb: support PTP/time PEROUT and EXTTS SDP functions on
82580/i354/i350 adapters
- ixgbevf: new PF -> VF mailbox API which avoids the risk of
mailbox corruption with ESXi
- iavf: support configuration of VLAN features of finer
granularity, stacked tags and filtering
- ice: PTP support for new E822 devices with sub-ns precision
- ice: support firmware activation without reboot
- Mellanox Ethernet NICs (mlx5):
- expose control over IRQ coalescing mode (CQE vs EQE) via ethtool
- support TC forwarding when tunnel encap and decap happen between
two ports of the same NIC
- dynamically size and allow disabling various features to save
resources for running in embedded / SmartNIC scenarios
- Broadcom Ethernet NICs (bnxt):
- use page frag allocator to improve Rx performance
- expose control over IRQ coalescing mode (CQE vs EQE) via ethtool
- Other Ethernet NICs:
- amd-xgbe: add Ryzen 6000 (Yellow Carp) Ethernet support
- Microsoft cloud/virtual NIC (mana):
- add XDP support (PASS, DROP, TX)
- Mellanox Ethernet switches (mlxsw):
- initial support for Spectrum-4 ASICs
- VxLAN with IPv6 underlay
- Marvell Ethernet switches (prestera):
- support flower flow templates
- add basic IP forwarding support
- NXP embedded Ethernet switches (ocelot & felix):
- support Per-Stream Filtering and Policing (PSFP)
- enable cut-through forwarding between ports by default
- support FDMA to improve packet Rx/Tx to CPU
- Other embedded switches:
- hellcreek: improve trapping management (STP and PTP) packets
- qca8k: support link aggregation and port mirroring
- Qualcomm 802.11ax WiFi (ath11k):
- qca6390, wcn6855: enable 802.11 power save mode in station mode
- BSS color change support
- WCN6855 hw2.1 support
- 11d scan offload support
- scan MAC address randomization support
- full monitor mode, only supported on QCN9074
- qca6390/wcn6855: report signal and tx bitrate
- qca6390: rfkill support
- qca6390/wcn6855: regdb.bin support
- Intel WiFi (iwlwifi):
- support SAR GEO Offset Mapping (SGOM) and Time-Aware-SAR (TAS)
in cooperation with the BIOS
- support for Optimized Connectivity Experience (OCE) scan
- support firmware API version 68
- lots of preparatory work for the upcoming Bz device family
- MediaTek WiFi (mt76):
- Specific Absorption Rate (SAR) support
- mt7921: 160 MHz channel support
- RealTek WiFi (rtw88):
- Specific Absorption Rate (SAR) support
- scan offload
- Other WiFi NICs
- ath10k: support fetching (pre-)calibration data from nvmem
- brcmfmac: configure keep-alive packet on suspend
- wcn36xx: beacon filter support"
* tag '5.17-net-next' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2048 commits)
tcp: tcp_send_challenge_ack delete useless param `skb`
net/qla3xxx: Remove useless DMA-32 fallback configuration
rocker: Remove useless DMA-32 fallback configuration
hinic: Remove useless DMA-32 fallback configuration
lan743x: Remove useless DMA-32 fallback configuration
net: enetc: Remove useless DMA-32 fallback configuration
cxgb4vf: Remove useless DMA-32 fallback configuration
cxgb4: Remove useless DMA-32 fallback configuration
cxgb3: Remove useless DMA-32 fallback configuration
bnx2x: Remove useless DMA-32 fallback configuration
et131x: Remove useless DMA-32 fallback configuration
be2net: Remove useless DMA-32 fallback configuration
vmxnet3: Remove useless DMA-32 fallback configuration
bna: Simplify DMA setting
net: alteon: Simplify DMA setting
myri10ge: Simplify DMA setting
qlcnic: Simplify DMA setting
net: allwinner: Fix print format
page_pool: remove spinlock in page_pool_refill_alloc_cache()
amt: fix wrong return type of amt_send_membership_update()
...
On arm64, user space counter access will be controlled differently
compared to x86. On x86, access in the strictest mode is enabled for all
tasks in an MM when any event is mmap'ed. For arm64, access is
explicitly requested for an event and only enabled when the event's
context is active. This avoids hooks into the arch context switch code
and gives better control of when access is enabled.
In order to configure user space access when the PMU is enabled, it is
necessary to know if any event (currently active or not) in the current
context has user space accessed enabled. Add a counter similar to other
counters in the context to avoid walking the event list every time.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211208201124.310740-3-robh@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
