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Fri, 8 Mar 2024 14:01:30 +0000 (GMT) X-AuditID: cbfec7f5-83dff70000002550-42-65eb1a3a6805 Received: from eusmtip1.samsung.com ( [203.254.199.221]) by eusmgms2.samsung.com (EUCPMTA) with SMTP id F6.60.10702.A3A1BE56; Fri, 8 Mar 2024 14:01:30 +0000 (GMT) Received: from [106.210.134.192] (unknown [106.210.134.192]) by eusmtip1.samsung.com (KnoxPortal) with ESMTPA id 20240308140128eusmtip198a00a4ac169037c128c18da0e798558~6zuRksdd41842018420eusmtip10; Fri, 8 Mar 2024 14:01:28 +0000 (GMT) Message-ID: Date: Fri, 8 Mar 2024 15:01:28 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512 Content-Language: en-US To: "Christoph Lameter (Ampere)" , Mark Rutland , "linux-pm@vger.kernel.org" , "Rafael J. Wysocki" , Viresh Kumar Cc: catalin.marinas@arm.com, Will Deacon , Jonathan.Cameron@huawei.com, Matteo.Carlini@arm.com, Valentin.Schneider@arm.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, Eric Mackay , dave.kleikamp@oracle.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux@armlinux.org.uk, robin.murphy@arm.com, vanshikonda@os.amperecomputing.com, yang@os.amperecomputing.com, Nishanth Menon , Stephen Boyd From: Marek Szyprowski In-Reply-To: <37099a57-b655-3b3a-56d0-5f7fbd49d7db@gentwo.org> Content-Transfer-Encoding: 8bit X-Brightmail-Tracker: H4sIAAAAAAAAA01Sf0xTVxjlvvf6WjrrnhXtHbhhGjGOsPoL4t1Y2MaMPJdNMFkysmxxjX0U BIppAYEYJdjBhpYVAhELSlV+gy0Wga04txakIOoouEqaijDAzQpORCcMVkZ5uPHfOec733e+ 7+bycGEB6c9LUKQySoU0SUzyidau2V/eesf/EbPNnrsNlRsbSXSt+yD6s/oUQDXlZzH084N+ HI17qrmo/ryDRKZRBwcNmMtJNNS4wEHTmk6ArCU/AlR1146hueoXGJqYuYWhs89KcGR5MsZB HsdlArVVzOLoodNFoObhLhKpXWFIU9nDfV9EN55rBPSAw47TP3UoaXXnJIc21X9L0qanRVy6 u3SOoJsrj9NT406CPjkwyKVtg20YPW16I2bV5/x3ZUxSQjqj3BrxFT/+wbnAw7OhGZe0tzjZ oCEkH/jyIBUKrxeNEvmAzxNStQBaXSOAJc8AnC7TYSyZBrC7o4n7ssXy/MmyqwbAx53NXJZM AWgZ1wGvS0BFwCsVJzleTFCbYPNdK8Hqa2DPmbElvI4KhPedpUtT11JS6G7T416MUyLoHKtY ivajhgAcMVzmsoViAma7RF5MUtth/mQ+6cW+i2HmouuA9QTCEy1luLcZUjl86Fr4mmT33g0v ms8TLF4L3bYry/dsgAs/sGmQygNQP3d/mWgBzP7dCVhXOHTd/ntxEm8x4k1oNG9l5Q+gu8DI 9cqQWg0HJ9ewS6yGRa2ncVYWwG9yhax7M9TZDP/FWvr6cS0Q61a8i27F/boV5+j+z9UDoh6I mDRVspxR7VQwRyQqabIqTSGXHExJNoHFL9vrsT3/HtS6pyRWgPGAFUAeLvYTEOghIxTIpJlZ jDLlgDItiVFZQQCPEIsEQbJARkjJpalMIsMcZpQvqxjP1z8bO1b1HpWMHXrl3p7h28GO8A2J xpxVE7KEm54u+4efRl4M1r8WVIitf6qJqKV20jcSHjV5Mn7zGb0karL1fXZhvHq+t2Yw4A+f nMjwnthj0i2qEtHMUMf6uDu6+AjPiH4+tuWUI27HkfADj2P2af/afDSu+OiuX31Cuo8b6m6q 7Wdmogqy8l/PSjnU+1FZXkmYaCIuL3GXav5GRjrkSGpaqvYOl9b5t/e3ujMNV6OjYzkyzX5J ut8nUZFRpfcsvhuLQ98u1O7J3bflRbxiR8zujZkNr17NuiYPIDTclMq9IV8U/rNO2O6WGDo0 0bXygTt+QV+GfWw+4Upt71LXGRu+i72gnuoTE6p46fZgXKmS/gsEGWeEIQQAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprPKsWRmVeSWpSXmKPExsVy+t/xu7pWUq9TDU5f4beYs34Nm8W+E8kW 75f1MFosnzOXyeLAs0vMFk//LWO3WLXwGpvFpsfXWC0u75rDZnFvzX9Wi8+9RxgtDk3dy2ix 9PpFJovfy74zWbz5cZbJYu6XqcwWBz88YbX4d20ji8X2+T+ZLV7eusNisfnBMTaLljumFr1L TrI7iHusmbeG0ePytYvMHvsPF3m0HHnL6rFpVSebx6ZPk9g9Tsz4zeKxeUm9x8ent1g8ui/f YPc4fmM7k8fnTXIBPFF6NkX5pSWpChn5xSW2StGGFkZ6hpYWekYmlnqGxuaxVkamSvp2Nimp OZllqUX6dgl6Gc/myRf8NKlYO+EsawPjap0uRk4OCQETiYNfPzB2MXJxCAksZZT4ffIoG0RC RuLktAZWCFtY4s+1LjaIoveMEg2vD7KAJHgF7CS2zO8GK2IRUJHYfP0QVFxQ4uTMJ2C2qIC8 xP1bM9hBbGGBRIlX2xcwg9jMAuISt57MZwIZKiJwj1HiyKqzLCAOs8AUFolPu7cB3cQBtM5W YsPXbJAGNgFDia63XWDXcQIt3jXpKCPEIDOJrq1dULa8RPPW2cwTGIVmIbljFpJ9s5C0zELS soCRZRWjSGppcW56brGRXnFibnFpXrpecn7uJkZgStl27OeWHYwrX33UO8TIxMF4iFGCg1lJ hJfF4mWqEG9KYmVValF+fFFpTmrxIUZTYGBMZJYSTc4HJrW8knhDMwNTQxMzSwNTSzNjJXFe z4KORCGB9MSS1OzU1ILUIpg+Jg5OqQYmIbVLxhOUuPZeNBG69Oie1rqjgWdYtvBmMCwXbGX2 rHu/4M/3D5Wr5zZ29xl/Co5+v1ThTaGiha7YxPAKg49Xjm1+/7zT/OurSpubH8wOX9W5Fqef ms7zsSMt4obtJ6Vk3tdaydyul39v2BOw9G5deXfvgdtKWZxRHybPykqMUuJjOxz2KSpVjfvO lW75tAvyApfPPKlcunjzYemPkzeuXbfcfcNZzfaNG+WP8gf/jzgidTP2kIjuh2039Lq2lFcy Nc596hb+Yf3UhjMcImySPf0+K9sV+IpFKvtmVQT/ahFz02Le83VKXZSo7TWDaT+P5d2rNTr+ 5OAUxgN6z9QVfvHc3j7FPr976skLwnumKbEUZyQaajEXFScCAI1Ije2yAwAA X-CMS-MailID: 20240308140130eucas1p1259c805a0b6491ce2f69c6fca0264b1f X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20240308140130eucas1p1259c805a0b6491ce2f69c6fca0264b1f X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20240308140130eucas1p1259c805a0b6491ce2f69c6fca0264b1f References: <37099a57-b655-3b3a-56d0-5f7fbd49d7db@gentwo.org> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 89BD218001C X-Stat-Signature: mg5j1k4srq5bc1mjq9nqb4wot5hzwzy5 X-Rspam-User: X-HE-Tag: 1709906493-107807 X-HE-Meta: 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 QpYG/MVT CrIzIPH1fl8Jq4hokgJSrUT1uLYHTnapfOMYdR6m18B6TJTjv/TB9jl/0bCtxwNu2f/b/Et8a3OGrHkA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Dear All, On 07.03.2024 02:45, Christoph Lameter (Ampere) wrote: > Currently defconfig selects NR_CPUS=256, but some vendors (e.g. Ampere > Computing) are planning to ship systems with 512 CPUs. So that all > CPUs on > these systems can be used with defconfig, we'd like to bump NR_CPUS to > 512. > Therefore this patch increases the default NR_CPUS from 256 to 512. > > As increasing NR_CPUS will increase the size of cpumasks, there's a > fear that > this might have a significant impact on stack usage due to code which > places > cpumasks on the stack. To mitigate that concern, we can select > CPUMASK_OFFSTACK. As that doesn't seem to be a problem today with > NR_CPUS=256, we only select this when NR_CPUS > 256. > > CPUMASK_OFFSTACK configures the cpumasks in the kernel to be > dynamically allocated. This was used in the X86 architecture in the > past to enable support for larger CPU configurations up to 8k cpus. > > With that is becomes possible to dynamically size the allocation of > the cpu bitmaps depending on the quantity of processors detected on > bootup. Memory used for cpumasks will increase if the kernel is > run on a machine with more cores. > > Further increases may be needed if ARM processor vendors start > supporting more processors. Given the current inflationary trends > in core counts from multiple processor manufacturers this may occur. > > There are minor regressions for hackbench. The kernel data size > for 512 cpus is smaller with offstack than with onstack. > > Benchmark results using hackbench average over 10 runs of > >     hackbench -s 512 -l 2000 -g 15 -f 25 -P > > on Altra 80 Core > > Support for 256 CPUs on stack. Baseline > >     7.8564 sec > > Support for 512 CUs on stack. > >     7.8713 sec + 0.18% > > 512 CPUS offstack > >     7.8916 sec + 0.44% > > Kernel size comparison: > >    text           data        filename                Difference to > onstack256 baseline > 25755648    9589248        vmlinuz-6.8.0-rc4-onstack256 > 25755648    9607680        vmlinuz-6.8.0-rc4-onstack512    +0.19% > 25755648    9603584        vmlinuz-6.8.0-rc4-offstack512    +0.14% > > Tested-by: Eric Mackay > Reviewed-by: Russell King (Oracle) > Signed-off-by: Christoph Lameter (Ampere) This patch landed in today's linux-next as commit 0499a78369ad ("ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512"). Unfortunately it triggers the following warning during boot on most of my ARM64-based test boards. Here is an example from Odroid-N2 board:  ------------[ cut here ]------------  WARNING: CPU: 4 PID: 63 at drivers/opp/core.c:2554 dev_pm_opp_set_config+0x390/0x710  Modules linked in: dw_hdmi_i2s_audio meson_gxl smsc onboard_usb_hub(+) rtc_pcf8563 panfrost snd_soc_meson_axg_sound_card drm_shmem_helper crct10dif_ce dwmac_generic snd_soc_meson_card_utils gpu_sched snd_soc_meson_g12a_toacodec snd_soc_meson_g12a_tohdmitx rc_odroid snd_soc_meson_codec_glue pwm_meson ao_cec_g12a meson_gxbb_wdt meson_ir snd_soc_meson_axg_frddr snd_soc_meson_axg_toddr snd_soc_meson_axg_tdmin meson_vdec(C) v4l2_mem2mem videobuf2_dma_contig snd_soc_meson_axg_tdmout videobuf2_memops axg_audio videobuf2_v4l2 sclk_div videodev reset_meson_audio_arb snd_soc_meson_axg_fifo clk_phase dwmac_meson8b stmmac_platform videobuf2_common mdio_mux_meson_g12a meson_drm meson_dw_hdmi rtc_meson_vrtc stmmac meson_ddr_pmu_g12 mc dw_hdmi drm_display_helper pcs_xpcs snd_soc_meson_t9015 meson_canvas gpio_fan display_connector snd_soc_meson_axg_tdm_interface snd_soc_simple_amplifier snd_soc_meson_axg_tdm_formatter nvmem_meson_efuse  hub 1-1:1.0: USB hub found  CPU: 4 PID: 63 Comm: kworker/u12:5 Tainted: G         C 6.8.0-rc3+ #14677  Hardware name: Hardkernel ODROID-N2 (DT)  Workqueue: events_unbound deferred_probe_work_func  pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)  pc : dev_pm_opp_set_config+0x390/0x710  lr : dev_pm_opp_set_config+0x5c/0x710  ...  Call trace:   dev_pm_opp_set_config+0x390/0x710   dt_cpufreq_probe+0x268/0x480   platform_probe+0x68/0xd8   really_probe+0x148/0x2b4   __driver_probe_device+0x78/0x12c   driver_probe_device+0xdc/0x164   __device_attach_driver+0xb8/0x138   bus_for_each_drv+0x84/0xe0   __device_attach+0xa8/0x1b0   device_initial_probe+0x14/0x20   bus_probe_device+0xb0/0xb4   deferred_probe_work_func+0x8c/0xc8   process_one_work+0x1ec/0x53c   worker_thread+0x298/0x408   kthread+0x124/0x128   ret_from_fork+0x10/0x20  irq event stamp: 317178  hardirqs last  enabled at (317177): [] ktime_get_coarse_real_ts64+0x10c/0x110  hardirqs last disabled at (317178): [] el1_dbg+0x24/0x8c  softirqs last  enabled at (315802): [] __do_softirq+0x4a0/0x4e8  softirqs last disabled at (315793): [] ____do_softirq+0x10/0x1c  ---[ end trace 0000000000000000 ]---  cpu cpu2: error -EBUSY: failed to set regulators  cpufreq-dt: probe of cpufreq-dt failed with error -16 It looks that cpufreq-dt and/or opp drivers needs some adjustments related with this change. > --- > > > Original post: https://www.spinics.net/lists/linux-mm/msg369701.html > V2: https://lkml.org/lkml/2024/2/7/505 > > > V1->V2 > > - Keep quotation marks > - Remove whiltespace damage > - Add tested by > > V2->V3: > - Add test results > - Rework descriptions > > >  arch/arm64/Kconfig | 16 +++++++++++++++- >  1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index aa7c1d435139..4e767dede47d 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -1427,7 +1427,21 @@ config SCHED_SMT >  config NR_CPUS >      int "Maximum number of CPUs (2-4096)" >      range 2 4096 > -    default "256" > +    default "512" > + > +# > +# Determines the placement of cpumasks. > +# > +# With CPUMASK_OFFSTACK the cpumasks are dynamically allocated. > +# Useful for machines with lots of core because it avoids increasing > +# the size of many of the data structures in the kernel. > +# > +# If this is off then the cpumasks have a static sizes and are > +# embedded within data structures. > +# > +    config CPUMASK_OFFSTACK > +    def_bool y > +    depends on NR_CPUS > 256 > >  config HOTPLUG_CPU >      bool "Support for hot-pluggable CPUs" Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland