| From: |
| guoren-AT-kernel.org |
| To: |
| paul.walmsley-AT-sifive.com, palmer-AT-dabbelt.com, guoren-AT-kernel.org, bjorn-AT-rivosinc.com, conor-AT-kernel.org, leobras-AT-redhat.com, peterz-AT-infradead.org, parri.andrea-AT-gmail.com, will-AT-kernel.org, longman-AT-redhat.com, boqun.feng-AT-gmail.com, arnd-AT-arndb.de, alexghiti-AT-rivosinc.com, ajones-AT-ventanamicro.com, rkrcmar-AT-ventanamicro.com |
| Subject: |
| [PATCH 0/3] riscv: Add PARAVIRT_SPINLOCKS support |
| Date: |
| Sat, 21 Dec 2024 22:39:14 -0500 |
| Message-ID: |
| <20241222033917.1754495-1-guoren@kernel.org> |
| Cc: |
| linux-riscv-AT-lists.infradead.org, linux-kernel-AT-vger.kernel.org, Guo Ren <guoren-AT-linux.alibaba.com> |
| Archive-link: |
| Article |
From: Guo Ren <guoren@linux.alibaba.com>
Paravirtualized spinlocks allow a unfair qspinlock to replace the
ticket-lock or native fair qspinlock implementation with something
virtualization-friendly, for example, halt the virtual CPU rather
than spinning.
You could observe the paravirt qspinlock internal work situation with
/sys/kernel/debug/tracing/trace:
ls /sys/kernel/debug/tracing/events/paravirt/
enable filter pv_kick pv_wait
echo 1 > /sys/kernel/debug/tracing/events/paravirt/enable
cat /sys/kernel/debug/tracing/trace
entries-in-buffer/entries-written: 33927/33927 #P:12
_-----=> irqs-off/BH-disabled
/ _----=> need-resched
| / _---=> hardirq/softirq
|| / _--=> preempt-depth
||| / _-=> migrate-disable
|||| / delay
TASK-PID CPU# ||||| TIMESTAMP FUNCTION
| | | ||||| | |
sh-100 [001] d..2. 28.312294: pv_wait: cpu 1 out of wfi
<idle>-0 [000] d.h4. 28.322030: pv_kick: cpu 0 kick target cpu 1
sh-100 [001] d..2. 30.982631: pv_wait: cpu 1 out of wfi
<idle>-0 [000] d.h4. 30.993289: pv_kick: cpu 0 kick target cpu 1
sh-100 [002] d..2. 44.987573: pv_wait: cpu 2 out of wfi
<idle>-0 [000] d.h4. 44.989000: pv_kick: cpu 0 kick target cpu 2
<idle>-0 [003] d.s3. 51.593978: pv_kick: cpu 3 kick target cpu 4
rcu_sched-15 [004] d..2. 51.595192: pv_wait: cpu 4 out of wfi
lock_torture_wr-115 [004] ...2. 52.656482: pv_kick: cpu 4 kick target cpu 2
lock_torture_wr-113 [002] d..2. 52.659146: pv_wait: cpu 2 out of wfi
lock_torture_wr-114 [008] d..2. 52.659507: pv_wait: cpu 8 out of wfi
lock_torture_wr-114 [008] d..2. 52.663503: pv_wait: cpu 8 out of wfi
lock_torture_wr-113 [002] ...2. 52.666128: pv_kick: cpu 2 kick target cpu 8
lock_torture_wr-114 [008] d..2. 52.667261: pv_wait: cpu 8 out of wfi
lock_torture_wr-114 [009] .n.2. 53.141515: pv_kick: cpu 9 kick target cpu 11
lock_torture_wr-113 [002] d..2. 53.143339: pv_wait: cpu 2 out of wfi
lock_torture_wr-116 [007] d..2. 53.143412: pv_wait: cpu 7 out of wfi
lock_torture_wr-118 [000] d..2. 53.143457: pv_wait: cpu 0 out of wfi
lock_torture_wr-115 [008] d..2. 53.143481: pv_wait: cpu 8 out of wfi
lock_torture_wr-117 [011] d..2. 53.143522: pv_wait: cpu 11 out of wfi
lock_torture_wr-117 [011] ...2. 53.143987: pv_kick: cpu 11 kick target cpu 8
lock_torture_wr-115 [008] ...2. 53.144269: pv_kick: cpu 8 kick target cpu 7
This series is split from [1].
[1]: https://lore.kernel.org/linux-riscv/20231225125847.277863...
Guo Ren (3):
RISC-V: paravirt: Add pvqspinlock KVM backend
RISC-V: paravirt: Add pvqspinlock frontend
RISC-V: paravirt: pvqspinlock: Add trace point for pv_kick/wait
arch/riscv/Kconfig | 12 +++
arch/riscv/include/asm/Kbuild | 1 -
arch/riscv/include/asm/kvm_vcpu_sbi.h | 1 +
arch/riscv/include/asm/qspinlock.h | 35 +++++++++
arch/riscv/include/asm/qspinlock_paravirt.h | 28 +++++++
arch/riscv/include/asm/sbi.h | 5 ++
arch/riscv/include/uapi/asm/kvm.h | 1 +
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/qspinlock_paravirt.c | 74 +++++++++++++++++++
arch/riscv/kernel/setup.c | 4 +
.../kernel/trace_events_filter_paravirt.h | 60 +++++++++++++++
arch/riscv/kvm/Makefile | 1 +
arch/riscv/kvm/vcpu_sbi.c | 4 +
arch/riscv/kvm/vcpu_sbi_pvlock.c | 57 ++++++++++++++
14 files changed, 283 insertions(+), 1 deletion(-)
create mode 100644 arch/riscv/include/asm/qspinlock.h
create mode 100644 arch/riscv/include/asm/qspinlock_paravirt.h
create mode 100644 arch/riscv/kernel/qspinlock_paravirt.c
create mode 100644 arch/riscv/kernel/trace_events_filter_paravirt.h
create mode 100644 arch/riscv/kvm/vcpu_sbi_pvlock.c
--
2.40.1
