On Sun, Sep 10, 2023 at 04:29:00AM -0400, guoren@xxxxxxxxxx wrote: > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > Combo spinlock could support queued and ticket in one Linux Image and > select them during boot time via errata mechanism. Here is the func > size (Bytes) comparison table below: > > TYPE : COMBO | TICKET | QUEUED > arch_spin_lock : 106 | 60 | 50 > arch_spin_unlock : 54 | 36 | 26 > arch_spin_trylock : 110 | 72 | 54 > arch_spin_is_locked : 48 | 34 | 20 > arch_spin_is_contended : 56 | 40 | 24 > rch_spin_value_unlocked : 48 | 34 | 24 > > One example of disassemble combo arch_spin_unlock: > 0xffffffff8000409c <+14>: nop # detour slot > 0xffffffff800040a0 <+18>: fence rw,w # queued spinlock start > 0xffffffff800040a4 <+22>: sb zero,0(a4) # queued spinlock end > 0xffffffff800040a8 <+26>: ld s0,8(sp) > 0xffffffff800040aa <+28>: addi sp,sp,16 > 0xffffffff800040ac <+30>: ret > 0xffffffff800040ae <+32>: lw a5,0(a4) # ticket spinlock start > 0xffffffff800040b0 <+34>: sext.w a5,a5 > 0xffffffff800040b2 <+36>: fence rw,w > 0xffffffff800040b6 <+40>: addiw a5,a5,1 > 0xffffffff800040b8 <+42>: slli a5,a5,0x30 > 0xffffffff800040ba <+44>: srli a5,a5,0x30 > 0xffffffff800040bc <+46>: sh a5,0(a4) # ticket spinlock end > 0xffffffff800040c0 <+50>: ld s0,8(sp) > 0xffffffff800040c2 <+52>: addi sp,sp,16 > 0xffffffff800040c4 <+54>: ret > > The qspinlock is smaller and faster than ticket-lock when all are in > fast-path, and combo spinlock could provide a compatible Linux Image > for different micro-arch design (weak/strict fwd guarantee LR/SC) > processors. > > Signed-off-by: Guo Ren <guoren@xxxxxxxxxx> > Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > --- > arch/riscv/Kconfig | 9 +++- > arch/riscv/include/asm/spinlock.h | 78 ++++++++++++++++++++++++++++++- > arch/riscv/kernel/setup.c | 14 ++++++ > 3 files changed, 98 insertions(+), 3 deletions(-) > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 7f39bfc75744..4bcff2860f48 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -473,7 +473,7 @@ config NODES_SHIFT > > choice > prompt "RISC-V spinlock type" > - default RISCV_TICKET_SPINLOCKS > + default RISCV_COMBO_SPINLOCKS > > config RISCV_TICKET_SPINLOCKS > bool "Using ticket spinlock" > @@ -485,6 +485,13 @@ config RISCV_QUEUED_SPINLOCKS > help > Make sure your micro arch LL/SC has a strong forward progress guarantee. > Otherwise, stay at ticket-lock. > + > +config RISCV_COMBO_SPINLOCKS > + bool "Using combo spinlock" > + depends on SMP && MMU > + select ARCH_USE_QUEUED_SPINLOCKS > + help > + Select queued spinlock or ticket-lock via errata. > endchoice > > config RISCV_ALTERNATIVE > diff --git a/arch/riscv/include/asm/spinlock.h b/arch/riscv/include/asm/spinlock.h > index c644a92d4548..8ea0fee80652 100644 > --- a/arch/riscv/include/asm/spinlock.h > +++ b/arch/riscv/include/asm/spinlock.h > @@ -7,11 +7,85 @@ > #define _Q_PENDING_LOOPS (1 << 9) > #endif > > +#ifdef CONFIG_RISCV_COMBO_SPINLOCKS > +#include <asm-generic/ticket_spinlock.h> > + > +#undef arch_spin_is_locked > +#undef arch_spin_is_contended > +#undef arch_spin_value_unlocked > +#undef arch_spin_lock > +#undef arch_spin_trylock > +#undef arch_spin_unlock > + > +#include <asm-generic/qspinlock.h> > +#include <linux/jump_label.h> > + > +#undef arch_spin_is_locked > +#undef arch_spin_is_contended > +#undef arch_spin_value_unlocked > +#undef arch_spin_lock > +#undef arch_spin_trylock > +#undef arch_spin_unlock Sorry, I forgot __no_arch_spinlock_redefine advice here. I would add it in v12. https://lore.kernel.org/linux-riscv/4cc7113a-0e4e-763a-cba2-7963bcd26c7a@xxxxxxxxxx/ > + > +DECLARE_STATIC_KEY_TRUE(combo_qspinlock_key); > + > +static __always_inline void arch_spin_lock(arch_spinlock_t *lock) > +{ > + if (static_branch_likely(&combo_qspinlock_key)) > + queued_spin_lock(lock); > + else > + ticket_spin_lock(lock); > +} > + > +static __always_inline bool arch_spin_trylock(arch_spinlock_t *lock) > +{ > + if (static_branch_likely(&combo_qspinlock_key)) > + return queued_spin_trylock(lock); > + else > + return ticket_spin_trylock(lock); > +} > + > +static __always_inline void arch_spin_unlock(arch_spinlock_t *lock) > +{ > + if (static_branch_likely(&combo_qspinlock_key)) > + queued_spin_unlock(lock); > + else > + ticket_spin_unlock(lock); > +} > + > +static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) > +{ > + if (static_branch_likely(&combo_qspinlock_key)) > + return queued_spin_value_unlocked(lock); > + else > + return ticket_spin_value_unlocked(lock); > +} > + > +static __always_inline int arch_spin_is_locked(arch_spinlock_t *lock) > +{ > + if (static_branch_likely(&combo_qspinlock_key)) > + return queued_spin_is_locked(lock); > + else > + return ticket_spin_is_locked(lock); > +} > + > +static __always_inline int arch_spin_is_contended(arch_spinlock_t *lock) > +{ > + if (static_branch_likely(&combo_qspinlock_key)) > + return queued_spin_is_contended(lock); > + else > + return ticket_spin_is_contended(lock); > +} > +#else /* CONFIG_RISCV_COMBO_SPINLOCKS */ > + > #ifdef CONFIG_QUEUED_SPINLOCKS > #include <asm/qspinlock.h> > -#include <asm/qrwlock.h> > #else > -#include <asm-generic/spinlock.h> > +#include <asm-generic/ticket_spinlock.h> > #endif > > +#endif /* CONFIG_RISCV_COMBO_SPINLOCKS */ > + > +#include <asm/qrwlock.h> > + > #endif /* __ASM_RISCV_SPINLOCK_H */ > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c > index 32c2e1eb71bd..a447cf360a18 100644 > --- a/arch/riscv/kernel/setup.c > +++ b/arch/riscv/kernel/setup.c > @@ -269,6 +269,18 @@ static void __init parse_dtb(void) > #endif > } > > +#ifdef CONFIG_RISCV_COMBO_SPINLOCKS > +DEFINE_STATIC_KEY_TRUE(combo_qspinlock_key); > +EXPORT_SYMBOL(combo_qspinlock_key); > +#endif > + > +static void __init riscv_spinlock_init(void) > +{ > +#ifdef CONFIG_RISCV_COMBO_SPINLOCKS > + static_branch_disable(&combo_qspinlock_key); > +#endif > +} > + > extern void __init init_rt_signal_env(void); > > void __init setup_arch(char **cmdline_p) > @@ -317,6 +329,8 @@ void __init setup_arch(char **cmdline_p) > riscv_isa_extension_available(NULL, ZICBOM)) > riscv_noncoherent_supported(); > riscv_set_dma_cache_alignment(); > + > + riscv_spinlock_init(); > } > > static int __init topology_init(void) > -- > 2.36.1 > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-riscv >
