Re: [v4 00/11] Improve RISC-V Perf support using SBI PMU and sscofpmf extension
From: Atish Patra <hidden>
Date: 2021-12-14 18:29:49
Also in:
linux-devicetree, linux-doc, linux-riscv, lkml
On Tue, Dec 14, 2021 at 1:14 AM Nikita Shubin [off-list ref] wrote:
Hello Atish! I get linker error if CONFIG_RISCV_PMU_LEGACY is not set: riscv64-unknown-linux-gnu-ld: drivers/perf/riscv_pmu_sbi.o: in function `pmu_sbi_device_probe': linux/drivers/perf/riscv_pmu_sbi.c:688: undefined reference to `riscv_pmu_legacy_init' It looks like you need some guards or a dummy function for riscv_pmu_legacy_init.
Ahh yes. Thanks for catching that. I will fix it in the next version.
On Mon, 25 Oct 2021 12:53:39 -0700 Atish Patra [off-list ref] wrote:quoted
This series adds improved perf support for RISC-V based system using SBI PMU extension[1] and Sscofpmf extension[2]. The SBI PMU extension allows the kernel to program the counters for different events and start/stop counters while the sscofpmf extension allows the counter overflow interrupt and privilege mode filtering. An hardware platform can leverage SBI PMU extension without the sscofpmf extension if it supports mcountinhibit and mcounteren. However, the reverse is not true. With both of these extension enabled, a platform can take advantage of all both event counting and sampling using perf tool. This series introduces a platform perf driver instead of a existing arch specific implementation. The new perf implementation has adopted a modular approach where most of the generic event handling is done in the core library while individual PMUs need to only implement necessary features specific to the PMU. This is easily extensible and any future RISC-V PMU implementation can leverage this. Currently, SBI PMU driver & legacy PMU driver are implemented as a part of this series. The legacy driver tries to reimplement the existing minimal perf under a new config to maintain backward compatibility. This implementation only allows monitoring of always running cycle/instruction counters. Moreover, they can not be started or stopped. In general, this is very limited and not very useful. That's why, I am not very keen to carry the support into the new driver. However, I don't want to break perf for any existing hardware platforms. If everybody agrees that we don't need legacy perf implementation for older implementation, I will be happy to drop PATCH 4. This series has been tested in Qemu (RV64 & RV32) and HiFive Unmatched. Qemu[5] & OpenSBI [3] patches are required to test it on Qemu and a dt patch required in U-Boot[6] for HiFive Unmatched. Qemu changes are not backward compatible. That means, you can not use perf anymore on older Qemu versions with latest OpenSBI and/or Kernel. However, newer kernel will just use legacy pmu driver if old OpenSBI is detected. The U-Boot patch is just an example that encodes few of the events defined in fu740 documentation [7] in the DT. We can update the DT to include all the events defined if required. Here is an output of perf stat/report while running perf benchmark with OpenSBI, Linux kernel and U-Boot patches applied. HiFive Unmatched: ================= perf stat -e cycles -e instructions -e L1-icache-load-misses -e branches -e branch-misses \ -e r0000000000000200 -e r0000000000000400 \ -e r0000000000000800 perf bench sched messaging -g 25 -l 15 # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 25 groups == 1000 processes run Total time: 0.826 [sec] Performance counter stats for 'perf bench sched messaging -g 25 -l 15': 3426710073 cycles (65.92%) 1348772808 instructions #0.39 insn per cycle (75.44%) 0 L1-icache-load-misses (72.28%) 201133996 branches (67.88%) 44663584 branch-misses #22.21% of all branches (35.01%) 248194747 r0000000000000200 (41.94%) --> Integer load instruction retired 156879950 r0000000000000400 (43.58%) --> Integer store instruction retired 6988678 r0000000000000800 (47.91%) --> Atomic memory operation retired 1.931335000 seconds time elapsed 1.100415000 seconds user 3.755176000 seconds sys QEMU: ========= Perf stat: ========= [root@fedora-riscv riscv]# perf stat -e r8000000000000005 -e r8000000000000007 \ -e r8000000000000006 -e r0000000000020002 -e r0000000000020004 -e branch-misses \ -e cache-misses -e dTLB-load-misses -e dTLB-store-misses -e iTLB-load-misses \ -e cycles -e instructions perf bench sched messaging -g 15 -l 10 \ Running with 15*40 (== 600) tasks. Time: 6.578 Performance counter stats for './hackbench -pipe 15 process': 1,794 r8000000000000005 (52.59%) --> SBI_PMU_FW_SET_TIMER 2,859 r8000000000000007 (60.74%) --> SBI_PMU_FW_IPI_RECVD 4,205 r8000000000000006 (68.71%) --> SBI_PMU_FW_IPI_SENT 0 r0000000000020002 (81.69%) <not counted> r0000000000020004 (0.00%) <not counted> branch-misses (0.00%) <not counted> cache-misses (0.00%) 7,878,328 dTLB-load-misses (15.60%) 680,270 dTLB-store-misses (28.45%) 8,287,931 iTLB-load-misses (39.24%) 20,008,506,675 cycles (48.60%) 21,484,427,932 instructions # 1.07 insn per cycle (56.60%) 1.681344735 seconds time elapsed 0.614460000 seconds user 8.313254000 seconds sys Perf record: ============ [root@fedora-riscv riscv]# perf record -e cycles -e instructions \ -e dTLB-load-misses -e dTLB-store-misses -e iTLB-load-misses -c 10000 \ perf bench sched messaging -g 15 -l 10 # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 15 groups == 600 processes run Total time: 1.261 [sec] [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.101 MB perf.data (845 samples) ] [root@fedora-riscv riscv]# perf report Available samples 407 cycles _ 407 instructions _ 18 dTLB-load-misses _ 2 dTLB-store-misses _ 11 iTLB-load-misses _ [1] https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/riscv-sbi.adoc [2] https://drive.google.com/file/d/171j4jFjIkKdj5LWcExphq4xG_2sihbfd/edit [3] https://github.com/atishp04/opensbi/tree/pmu_sscofpmf_v2 [4] https://github.com/atishp04/linux/tree/riscv_pmu_v4 [5] https://github.com/atishp04/qemu/tree/riscv_pmu_v3 [6] https://github.com/atishp04/u-boot/tree/hifive_unmatched_dt_pmu [7] https://sifive.cdn.prismic.io/sifive/de1491e5-077c-461d-9605-e8a0ce57337d_fu740-c000-manual-v1p3.pdf Changes from v3->v4: 1. Do not proceed overflow handler if event doesn't set for sampling. 2. overflow status register is only read after counters are stopped. 3. Added the PMU DT node for HiFive Unmatched. Changes from v2->v3: 1. Added interrupt overflow support. 2. Cleaned up legacy driver initialization. 3. Supports perf record now. 4. Added the DT binding and maintainers file. 5. Changed cpu hotplug notifier to be multi-state. 6. OpenSBI doesn't disable cycle/instret counter during boot. Update the perf code to disable all the counter during the boot. Changes from v1->v2 1. Implemented the latest SBI PMU extension specification. 2. The core platform driver was changed to operate as a library while only sbi based PMU is built as a driver. The legacy one is just a fallback if SBI PMU extension is not available. Atish Patra (11): RISC-V: Remove the current perf implementation RISC-V: Add CSR encodings for all HPMCOUNTERS RISC-V: Add a perf core library for pmu drivers RISC-V: Add a simple platform driver for RISC-V legacy perf RISC-V: Add RISC-V SBI PMU extension definitions dt-binding: pmu: Add RISC-V PMU DT bindings RISC-V: Add perf platform driver based on SBI PMU extension RISC-V: Add interrupt support for perf Documentation: riscv: Remove the old documentation riscv: dts: fu740: Add pmu node MAINTAINERS: Add entry for RISC-V PMU drivers .../devicetree/bindings/perf/riscv,pmu.yaml | 51 ++ Documentation/riscv/pmu.rst | 255 ------ MAINTAINERS | 10 + arch/riscv/Kconfig | 13 - arch/riscv/boot/dts/sifive/fu740-c000.dtsi | 3 + arch/riscv/include/asm/csr.h | 66 +- arch/riscv/include/asm/perf_event.h | 72 -- arch/riscv/include/asm/sbi.h | 97 +++ arch/riscv/kernel/Makefile | 1 - arch/riscv/kernel/perf_event.c | 485 ------------ drivers/perf/Kconfig | 25 + drivers/perf/Makefile | 5 + drivers/perf/riscv_pmu.c | 331 ++++++++ drivers/perf/riscv_pmu_legacy.c | 143 ++++ drivers/perf/riscv_pmu_sbi.c | 732 ++++++++++++++++++ include/linux/cpuhotplug.h | 1 + include/linux/perf/riscv_pmu.h | 69 ++ 17 files changed, 1532 insertions(+), 827 deletions(-) create mode 100644 Documentation/devicetree/bindings/perf/riscv,pmu.yaml delete mode 100644 Documentation/riscv/pmu.rst delete mode 100644 arch/riscv/kernel/perf_event.c create mode 100644 drivers/perf/riscv_pmu.c create mode 100644 drivers/perf/riscv_pmu_legacy.c create mode 100644 drivers/perf/riscv_pmu_sbi.c create mode 100644 include/linux/perf/riscv_pmu.h -- 2.31.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv_______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
-- Regards, Atish