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scx: Make task_on_scx() take const task_struct #32

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task_on_scx() takes a struct task_struct *p, but it's called by __task_prio() in CONFIG_SCHED_CORE which takes a const struct task_struct *. This can cause the build to fail due to incompatible pointer types:

kernel/sched/core.c:170:18: error: passing 'const struct task_struct *' to parameter of type 'struct task_struct *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
if (task_on_scx(p))
^
kernel/sched/ext.h:124:52: note: passing argument to parameter 'p' here static inline bool task_on_scx(struct task_struct *p)

Fix task_on_scx() so this doesn't happen.

task_on_scx() takes a struct task_struct *p, but it's called by
__task_prio() in CONFIG_SCHED_CORE which takes a const struct
task_struct *. This can cause the build to fail due to incompatible
pointer types:

kernel/sched/core.c:170:18: error: passing 'const struct task_struct *' to parameter of type 'struct task_struct *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
        if (task_on_scx(p))
                        ^
kernel/sched/ext.h:124:52: note: passing argument to parameter 'p' here
static inline bool task_on_scx(struct task_struct *p)

Fix task_on_scx() so this doesn't happen.

Signed-off-by: David Vernet <void@manifault.com>
@Byte-Lab Byte-Lab requested a review from htejun July 12, 2023 19:08
@htejun htejun merged commit aca7309 into sched_ext Jul 12, 2023
@Byte-Lab Byte-Lab deleted the task_scx_const branch July 12, 2023 19:23
htejun pushed a commit that referenced this pull request Feb 27, 2024
 ------------[ cut here ]------------
 memcpy: detected field-spanning write (size 56) of single field "eseg->inline_hdr.start" at /var/lib/dkms/mlnx-ofed-kernel/5.8/build/drivers/infiniband/hw/mlx5/wr.c:131 (size 2)
 WARNING: CPU: 0 PID: 293779 at /var/lib/dkms/mlnx-ofed-kernel/5.8/build/drivers/infiniband/hw/mlx5/wr.c:131 mlx5_ib_post_send+0x191b/0x1a60 [mlx5_ib]
 Modules linked in: 8021q garp mrp stp llc rdma_ucm(OE) rdma_cm(OE) iw_cm(OE) ib_ipoib(OE) ib_cm(OE) ib_umad(OE) mlx5_ib(OE) ib_uverbs(OE) ib_core(OE) mlx5_core(OE) pci_hyperv_intf mlxdevm(OE) mlx_compat(OE) tls mlxfw(OE) psample nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables libcrc32c nfnetlink mst_pciconf(OE) knem(OE) vfio_pci vfio_pci_core vfio_iommu_type1 vfio iommufd irqbypass cuse nfsv3 nfs fscache netfs xfrm_user xfrm_algo ipmi_devintf ipmi_msghandler binfmt_misc crct10dif_pclmul crc32_pclmul polyval_clmulni polyval_generic ghash_clmulni_intel sha512_ssse3 snd_pcsp aesni_intel crypto_simd cryptd snd_pcm snd_timer joydev snd soundcore input_leds serio_raw evbug nfsd auth_rpcgss nfs_acl lockd grace sch_fq_codel sunrpc drm efi_pstore ip_tables x_tables autofs4 psmouse virtio_net net_failover failover floppy
  [last unloaded: mlx_compat(OE)]
 CPU: 0 PID: 293779 Comm: ssh Tainted: G           OE      6.2.0-32-generic #32~22.04.1-Ubuntu
 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
 RIP: 0010:mlx5_ib_post_send+0x191b/0x1a60 [mlx5_ib]
 Code: 0c 01 00 a8 01 75 25 48 8b 75 a0 b9 02 00 00 00 48 c7 c2 10 5b fd c0 48 c7 c7 80 5b fd c0 c6 05 57 0c 03 00 01 e8 95 4d 93 da <0f> 0b 44 8b 4d b0 4c 8b 45 c8 48 8b 4d c0 e9 49 fb ff ff 41 0f b7
 RSP: 0018:ffffb5b48478b570 EFLAGS: 00010046
 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
 RBP: ffffb5b48478b628 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000000 R12: ffffb5b48478b5e8
 R13: ffff963a3c609b5e R14: ffff9639c3fbd800 R15: ffffb5b480475a80
 FS:  00007fc03b444c80(0000) GS:ffff963a3dc00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000556f46bdf000 CR3: 0000000006ac6003 CR4: 00000000003706f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  <TASK>
  ? show_regs+0x72/0x90
  ? mlx5_ib_post_send+0x191b/0x1a60 [mlx5_ib]
  ? __warn+0x8d/0x160
  ? mlx5_ib_post_send+0x191b/0x1a60 [mlx5_ib]
  ? report_bug+0x1bb/0x1d0
  ? handle_bug+0x46/0x90
  ? exc_invalid_op+0x19/0x80
  ? asm_exc_invalid_op+0x1b/0x20
  ? mlx5_ib_post_send+0x191b/0x1a60 [mlx5_ib]
  mlx5_ib_post_send_nodrain+0xb/0x20 [mlx5_ib]
  ipoib_send+0x2ec/0x770 [ib_ipoib]
  ipoib_start_xmit+0x5a0/0x770 [ib_ipoib]
  dev_hard_start_xmit+0x8e/0x1e0
  ? validate_xmit_skb_list+0x4d/0x80
  sch_direct_xmit+0x116/0x3a0
  __dev_xmit_skb+0x1fd/0x580
  __dev_queue_xmit+0x284/0x6b0
  ? _raw_spin_unlock_irq+0xe/0x50
  ? __flush_work.isra.0+0x20d/0x370
  ? push_pseudo_header+0x17/0x40 [ib_ipoib]
  neigh_connected_output+0xcd/0x110
  ip_finish_output2+0x179/0x480
  ? __smp_call_single_queue+0x61/0xa0
  __ip_finish_output+0xc3/0x190
  ip_finish_output+0x2e/0xf0
  ip_output+0x78/0x110
  ? __pfx_ip_finish_output+0x10/0x10
  ip_local_out+0x64/0x70
  __ip_queue_xmit+0x18a/0x460
  ip_queue_xmit+0x15/0x30
  __tcp_transmit_skb+0x914/0x9c0
  tcp_write_xmit+0x334/0x8d0
  tcp_push_one+0x3c/0x60
  tcp_sendmsg_locked+0x2e1/0xac0
  tcp_sendmsg+0x2d/0x50
  inet_sendmsg+0x43/0x90
  sock_sendmsg+0x68/0x80
  sock_write_iter+0x93/0x100
  vfs_write+0x326/0x3c0
  ksys_write+0xbd/0xf0
  ? do_syscall_64+0x69/0x90
  __x64_sys_write+0x19/0x30
  do_syscall_64+0x59/0x90
  ? do_user_addr_fault+0x1d0/0x640
  ? exit_to_user_mode_prepare+0x3b/0xd0
  ? irqentry_exit_to_user_mode+0x9/0x20
  ? irqentry_exit+0x43/0x50
  ? exc_page_fault+0x92/0x1b0
  entry_SYSCALL_64_after_hwframe+0x72/0xdc
 RIP: 0033:0x7fc03ad14a37
 Code: 10 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
 RSP: 002b:00007ffdf8697fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
 RAX: ffffffffffffffda RBX: 0000000000008024 RCX: 00007fc03ad14a37
 RDX: 0000000000008024 RSI: 0000556f46bd8270 RDI: 0000000000000003
 RBP: 0000556f46bb1800 R08: 0000000000007fe3 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
 R13: 0000556f46bc66b0 R14: 000000000000000a R15: 0000556f46bb2f50
  </TASK>
 ---[ end trace 0000000000000000 ]---

Link: https://lore.kernel.org/r/8228ad34bd1a25047586270f7b1fb4ddcd046282.1706433934.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
htejun pushed a commit that referenced this pull request Mar 5, 2024
Enabling CONFIG_PROVE_RCU_LIST raises many warnings in wilc driver, even on
some places already protected by a read critical section. An example of
such case is in wilc_get_available_idx:

=============================
WARNING: suspicious RCU usage
6.8.0-rc1+ #32 Not tainted
-----------------------------
drivers/net/wireless/microchip/wilc1000/netdev.c:944 RCU-list traversed in non-reader section!!
[...]
stack backtrace:
CPU: 0 PID: 26 Comm: kworker/0:3 Not tainted 6.8.0-rc1+ #32
Hardware name: Atmel SAMA5
Workqueue: events_freezable mmc_rescan
 unwind_backtrace from show_stack+0x18/0x1c
 show_stack from dump_stack_lvl+0x34/0x58
 dump_stack_lvl from wilc_netdev_ifc_init+0x788/0x8ec
 wilc_netdev_ifc_init from wilc_cfg80211_init+0x690/0x910
 wilc_cfg80211_init from wilc_sdio_probe+0x168/0x490
 wilc_sdio_probe from sdio_bus_probe+0x230/0x3f4
 sdio_bus_probe from really_probe+0x270/0xdf4
 really_probe from __driver_probe_device+0x1dc/0x580
 __driver_probe_device from driver_probe_device+0x60/0x140
 driver_probe_device from __device_attach_driver+0x268/0x364
 __device_attach_driver from bus_for_each_drv+0x15c/0x1cc
 bus_for_each_drv from __device_attach+0x1ec/0x3e8
 __device_attach from bus_probe_device+0x190/0x1c0
 bus_probe_device from device_add+0x10dc/0x18e4
 device_add from sdio_add_func+0x1c0/0x2c0
 sdio_add_func from mmc_attach_sdio+0xa08/0xe1c
 mmc_attach_sdio from mmc_rescan+0xa00/0xfe0
 mmc_rescan from process_one_work+0x8d4/0x169c
 process_one_work from worker_thread+0x8cc/0x1340
 worker_thread from kthread+0x448/0x510
 kthread from ret_from_fork+0x14/0x28

This warning is due to the section being protected by a srcu critical read
section, but the list traversal being done with classic RCU API. Fix the
warning by using corresponding SRCU read lock/unlock APIs. While doing so,
since we always manipulate the same list (managed through a pointer
embedded in struct_wilc), add a macro to reduce the corresponding
boilerplate in each call site.

Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240215-wilc_fix_rcu_usage-v1-2-f610e46c6f82@bootlin.com
arighi pushed a commit to arighi/sched_ext that referenced this pull request Jun 7, 2024
BugLink: https://bugs.launchpad.net/bugs/2065899

[ Upstream commit 5ee0d47 ]

Currently, when using non-blocking commits, we can see the following
kernel warning:

[  110.908514] ------------[ cut here ]------------
[  110.908529] refcount_t: underflow; use-after-free.
[  110.908620] WARNING: CPU: 0 PID: 1866 at lib/refcount.c:87 refcount_dec_not_one+0xb8/0xc0
[  110.908664] Modules linked in: rfcomm snd_seq_dummy snd_hrtimer snd_seq snd_seq_device cmac algif_hash aes_arm64 aes_generic algif_skcipher af_alg bnep hid_logitech_hidpp vc4 brcmfmac hci_uart btbcm brcmutil bluetooth snd_soc_hdmi_codec cfg80211 cec drm_display_helper drm_dma_helper drm_kms_helper snd_soc_core snd_compress snd_pcm_dmaengine fb_sys_fops sysimgblt syscopyarea sysfillrect raspberrypi_hwmon ecdh_generic ecc rfkill libaes i2c_bcm2835 binfmt_misc joydev snd_bcm2835(C) bcm2835_codec(C) bcm2835_isp(C) v4l2_mem2mem videobuf2_dma_contig snd_pcm bcm2835_v4l2(C) raspberrypi_gpiomem bcm2835_mmal_vchiq(C) videobuf2_v4l2 snd_timer videobuf2_vmalloc videobuf2_memops videobuf2_common snd videodev vc_sm_cma(C) mc hid_logitech_dj uio_pdrv_genirq uio i2c_dev drm fuse dm_mod drm_panel_orientation_quirks backlight ip_tables x_tables ipv6
[  110.909086] CPU: 0 PID: 1866 Comm: kodi.bin Tainted: G         C         6.1.66-v8+ sched-ext#32
[  110.909104] Hardware name: Raspberry Pi 3 Model B Rev 1.2 (DT)
[  110.909114] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[  110.909132] pc : refcount_dec_not_one+0xb8/0xc0
[  110.909152] lr : refcount_dec_not_one+0xb4/0xc0
[  110.909170] sp : ffffffc00913b9c0
[  110.909177] x29: ffffffc00913b9c0 x28: 000000556969bbb0 x27: 000000556990df60
[  110.909205] x26: 0000000000000002 x25: 0000000000000004 x24: ffffff8004448480
[  110.909230] x23: ffffff800570b500 x22: ffffff802e03a7bc x21: ffffffecfca68c78
[  110.909257] x20: ffffff8002b42000 x19: ffffff802e03a600 x18: 0000000000000000
[  110.909283] x17: 0000000000000011 x16: ffffffffffffffff x15: 0000000000000004
[  110.909308] x14: 0000000000000fff x13: ffffffed577e47e0 x12: 0000000000000003
[  110.909333] x11: 0000000000000000 x10: 0000000000000027 x9 : c912d0d083728c00
[  110.909359] x8 : c912d0d083728c00 x7 : 65646e75203a745f x6 : 746e756f63666572
[  110.909384] x5 : ffffffed579f62ee x4 : ffffffed579eb01e x3 : 0000000000000000
[  110.909409] x2 : 0000000000000000 x1 : ffffffc00913b750 x0 : 0000000000000001
[  110.909434] Call trace:
[  110.909441]  refcount_dec_not_one+0xb8/0xc0
[  110.909461]  vc4_bo_dec_usecnt+0x4c/0x1b0 [vc4]
[  110.909903]  vc4_cleanup_fb+0x44/0x50 [vc4]
[  110.910315]  drm_atomic_helper_cleanup_planes+0x88/0xa4 [drm_kms_helper]
[  110.910669]  vc4_atomic_commit_tail+0x390/0x9dc [vc4]
[  110.911079]  commit_tail+0xb0/0x164 [drm_kms_helper]
[  110.911397]  drm_atomic_helper_commit+0x1d0/0x1f0 [drm_kms_helper]
[  110.911716]  drm_atomic_commit+0xb0/0xdc [drm]
[  110.912569]  drm_mode_atomic_ioctl+0x348/0x4b8 [drm]
[  110.913330]  drm_ioctl_kernel+0xec/0x15c [drm]
[  110.914091]  drm_ioctl+0x24c/0x3b0 [drm]
[  110.914850]  __arm64_sys_ioctl+0x9c/0xd4
[  110.914873]  invoke_syscall+0x4c/0x114
[  110.914897]  el0_svc_common+0xd0/0x118
[  110.914917]  do_el0_svc+0x38/0xd0
[  110.914936]  el0_svc+0x30/0x8c
[  110.914958]  el0t_64_sync_handler+0x84/0xf0
[  110.914979]  el0t_64_sync+0x18c/0x190
[  110.914996] ---[ end trace 0000000000000000 ]---

This happens because, although `prepare_fb` and `cleanup_fb` are
perfectly balanced, we cannot guarantee consistency in the check
plane->state->fb == state->fb. This means that sometimes we can increase
the refcount in `prepare_fb` and don't decrease it in `cleanup_fb`. The
opposite can also be true.

In fact, the struct drm_plane .state shouldn't be accessed directly
but instead, the `drm_atomic_get_new_plane_state()` helper function should
be used. So, we could stick to this check, but using
`drm_atomic_get_new_plane_state()`. But actually, this check is not really
needed. We can increase and decrease the refcount symmetrically without
problems.

This is going to make the code more simple and consistent.

Signed-off-by: Maíra Canal <mcanal@igalia.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240105175908.242000-1-mcanal@igalia.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>
htejun pushed a commit that referenced this pull request Jun 17, 2024
Inline calls to bpf_get_smp_processor_id() helper in the JIT by emitting
a read from struct thread_info. The SP_EL0 system register holds the
pointer to the task_struct and thread_info is the first member of this
struct. We can read the cpu number from the thread_info.

Here is how the ARM64 JITed assembly changes after this commit:

                                      ARM64 JIT
                                     ===========

              BEFORE                                    AFTER
             --------                                  -------

int cpu = bpf_get_smp_processor_id();        int cpu = bpf_get_smp_processor_id();

mov     x10, #0xfffffffffffff4d0             mrs     x10, sp_el0
movk    x10, #0x802b, lsl #16                ldr     w7, [x10, #24]
movk    x10, #0x8000, lsl #32
blr     x10
add     x7, x0, #0x0

               Performance improvement using benchmark[1]

./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc

+---------------+-------------------+-------------------+--------------+
|      Name     |      Before       |        After      |   % change   |
|---------------+-------------------+-------------------+--------------|
| glob-arr-inc  | 23.380 ± 1.675M/s | 25.893 ± 0.026M/s |   + 10.74%   |
| arr-inc       | 23.928 ± 0.034M/s | 25.213 ± 0.063M/s |   + 5.37%    |
| hash-inc      | 12.352 ± 0.005M/s | 12.609 ± 0.013M/s |   + 2.08%    |
+---------------+-------------------+-------------------+--------------+

[1] anakryiko/linux@8dec900975ef

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240502151854.9810-5-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
htejun pushed a commit that referenced this pull request Jun 17, 2024
Puranjay Mohan says:

====================
bpf: Inline helpers in arm64 and riscv JITs

Changes in v5 -> v6:
arm64 v5: https://lore.kernel.org/all/20240430234739.79185-1-puranjay@kernel.org/
riscv v2: https://lore.kernel.org/all/20240430175834.33152-1-puranjay@kernel.org/
- Combine riscv and arm64 changes in single series
- Some coding style fixes

Changes in v4 -> v5:
v4: https://lore.kernel.org/all/20240429131647.50165-1-puranjay@kernel.org/
- Implement the inlining of the bpf_get_smp_processor_id() in the JIT.

NOTE: This needs to be based on:
https://lore.kernel.org/all/20240430175834.33152-1-puranjay@kernel.org/
to be built.

Manual run of bpf-ci with this series rebased on above:
kernel-patches/bpf#6929

Changes in v3 -> v4:
v3: https://lore.kernel.org/all/20240426121349.97651-1-puranjay@kernel.org/
- Fix coding style issue related to C89 standards.

Changes in v2 -> v3:
v2: https://lore.kernel.org/all/20240424173550.16359-1-puranjay@kernel.org/
- Fixed the xlated dump of percpu mov to "r0 = &(void __percpu *)(r0)"
- Made ARM64 and x86-64 use the same code for inlining. The only difference
  that remains is the per-cpu address of the cpu_number.

Changes in v1 -> v2:
v1: https://lore.kernel.org/all/20240405091707.66675-1-puranjay12@gmail.com/
- Add a patch to inline bpf_get_smp_processor_id()
- Fix an issue in MRS instruction encoding as pointed out by Will
- Remove CONFIG_SMP check because arm64 kernel always compiles with CONFIG_SMP

This series adds the support of internal only per-CPU instructions and inlines
the bpf_get_smp_processor_id() helper call for ARM64 and RISC-V BPF JITs.

Here is an example of calls to bpf_get_smp_processor_id() and
percpu_array_map_lookup_elem() before and after this series on ARM64.

                                         BPF
                                        =====
              BEFORE                                       AFTER
             --------                                     -------

int cpu = bpf_get_smp_processor_id();           int cpu = bpf_get_smp_processor_id();
(85) call bpf_get_smp_processor_id#229032       (85) call bpf_get_smp_processor_id#8

p = bpf_map_lookup_elem(map, &zero);            p = bpf_map_lookup_elem(map, &zero);
(18) r1 = map[id:78]                            (18) r1 = map[id:153]
(18) r2 = map[id:82][0]+65536                   (18) r2 = map[id:157][0]+65536
(85) call percpu_array_map_lookup_elem#313512   (07) r1 += 496
                                                (61) r0 = *(u32 *)(r2 +0)
                                                (35) if r0 >= 0x1 goto pc+5
                                                (67) r0 <<= 3
                                                (0f) r0 += r1
                                                (79) r0 = *(u64 *)(r0 +0)
                                                (bf) r0 = &(void __percpu *)(r0)
                                                (05) goto pc+1
                                                (b7) r0 = 0

                                      ARM64 JIT
                                     ===========

              BEFORE                                       AFTER
             --------                                     -------

int cpu = bpf_get_smp_processor_id();           int cpu = bpf_get_smp_processor_id();
mov     x10, #0xfffffffffffff4d0                mrs     x10, sp_el0
movk    x10, #0x802b, lsl #16                   ldr     w7, [x10, #24]
movk    x10, #0x8000, lsl #32
blr     x10
add     x7, x0, #0x0

p = bpf_map_lookup_elem(map, &zero);            p = bpf_map_lookup_elem(map, &zero);
mov     x0, #0xffff0003ffffffff                 mov     x0, #0xffff0003ffffffff
movk    x0, #0xce5c, lsl #16                    movk    x0, #0xe0f3, lsl #16
movk    x0, #0xca00                             movk    x0, #0x7c00
mov     x1, #0xffff8000ffffffff                 mov     x1, #0xffff8000ffffffff
movk    x1, #0x8bdb, lsl #16                    movk    x1, #0xb0c7, lsl #16
movk    x1, #0x6000                             movk    x1, #0xe000
mov     x10, #0xffffffffffff3ed0                add     x0, x0, #0x1f0
movk    x10, #0x802d, lsl #16                   ldr     w7, [x1]
movk    x10, #0x8000, lsl #32                   cmp     x7, #0x1
blr     x10                                     b.cs    0x0000000000000090
add     x7, x0, #0x0                            lsl     x7, x7, #3
                                                add     x7, x7, x0
                                                ldr     x7, [x7]
                                                mrs     x10, tpidr_el1
                                                add     x7, x7, x10
                                                b       0x0000000000000094
                                                mov     x7, #0x0

              Performance improvement found using benchmark[1]

./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc

  +---------------+-------------------+-------------------+--------------+
  |      Name     |      Before       |        After      |   % change   |
  |---------------+-------------------+-------------------+--------------|
  | glob-arr-inc  | 23.380 ± 1.675M/s | 25.893 ± 0.026M/s |   + 10.74%   |
  | arr-inc       | 23.928 ± 0.034M/s | 25.213 ± 0.063M/s |   + 5.37%    |
  | hash-inc      | 12.352 ± 0.005M/s | 12.609 ± 0.013M/s |   + 2.08%    |
  +---------------+-------------------+-------------------+--------------+

[1] anakryiko/linux@8dec900975ef

             RISCV64 JIT output for `call bpf_get_smp_processor_id`
            =======================================================

                  Before                           After
                 --------                         -------

           auipc   t1,0x848c                  ld    a5,32(tp)
           jalr    604(t1)
           mv      a5,a0

  Benchmark using [1] on Qemu.

  ./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc

  +---------------+------------------+------------------+--------------+
  |      Name     |     Before       |       After      |   % change   |
  |---------------+------------------+------------------+--------------|
  | glob-arr-inc  | 1.077 ± 0.006M/s | 1.336 ± 0.010M/s |   + 24.04%   |
  | arr-inc       | 1.078 ± 0.002M/s | 1.332 ± 0.015M/s |   + 23.56%   |
  | hash-inc      | 0.494 ± 0.004M/s | 0.653 ± 0.001M/s |   + 32.18%   |
  +---------------+------------------+------------------+--------------+
====================

Link: https://lore.kernel.org/r/20240502151854.9810-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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