On Wed, Sep 13, 2023 at 05:37:01PM -0300, Leonardo Bras wrote: > On Sun, Sep 10, 2023 at 07:06:23AM -0400, Guo Ren wrote: > > 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/ > > > > Please check a reply to a previous patch I sent earlier: I think these > #undef can be avoided. > > > > + > > > +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 */ > > > + Also, those functions all reproduce the same behavior, so maybe it would be better to keep that behavior in a macro such as: #define COMBO_SPINLOCK_DECLARE(f) \ static __always_inline int arch_spin_ ## f(arch_spinlock_t *lock) \ { \ if (static_branch_likely(&combo_qspinlock_key)) \ return queued_spin_ ## f(lock); \ else \ return ticket_spin_ ## f(lock); \ } COMBO_SPINLOCK_DECLARE(lock) COMBO_SPINLOCK_DECLARE(trylock) COMBO_SPINLOCK_DECLARE(unlock) COMBO_SPINLOCK_DECLARE(value_unlocked) COMBO_SPINLOCK_DECLARE(is_locked) COMBO_SPINLOCK_DECLARE(is_contended) Does that make sense? Thanks! Leo > > > #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 > > > > >
