From mboxrd@z Thu Jan 1 00:00:00 1970 From: Helge Deller Subject: Re: [PATCH] parisc: Align locks for LWS syscalls to L1 cache size Date: Wed, 2 Sep 2015 22:29:11 +0200 Message-ID: <20150902202911.GA5164@ls3530.box> References: <20150902193840.GA4499@ls3530.box> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: John David Anglin , linux-parisc@vger.kernel.org, James Bottomley Return-path: In-Reply-To: List-ID: List-Id: linux-parisc.vger.kernel.org parisc: Align locks for LWS syscalls to L1 cache size (v2) Align the locks for the Light-weight-syscall (LWS) which are used for atomic userspace operations (e.g. gcc atomic builtins) on L1 cache boundaries. This should speed up LWS calls on PA20 systems. Reported-by: John David Anglin Signed-off-by: Helge Deller diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S index 7ef22e3..80c2306 100644 --- a/arch/parisc/kernel/syscall.S +++ b/arch/parisc/kernel/syscall.S @@ -561,9 +561,9 @@ lws_compare_and_swap: extru %r26, 27, 4, %r20 /* Find lock to use, the hash is either one of 0 to - 15, multiplied by 16 (keep it 16-byte aligned) + 15, multiplied by L1_CACHE_BYTES (keep it L1 cache aligned) and add to the lock table offset. */ - shlw %r20, 4, %r20 + shlw %r20, L1_CACHE_SHIFT, %r20 add %r20, %r28, %r20 # if ENABLE_LWS_DEBUG @@ -751,9 +751,9 @@ cas2_lock_start: extru %r26, 27, 4, %r20 /* Find lock to use, the hash is either one of 0 to - 15, multiplied by 16 (keep it 16-byte aligned) + 15, multiplied by L1_CACHE_BYTES (keep it L1 cache aligned) and add to the lock table offset. */ - shlw %r20, 4, %r20 + shlw %r20, L1_CACHE_SHIFT, %r20 add %r20, %r28, %r20 rsm PSW_SM_I, %r0 /* Disable interrupts */ @@ -931,11 +931,9 @@ END(sys_call_table64) ENTRY(lws_lock_start) /* lws locks */ .rept 16 - /* Keep locks aligned at 16-bytes */ + /* Keep locks aligned to L1_CACHE_BYTES */ .word 1 - .word 0 - .word 0 - .word 0 + .align L1_CACHE_BYTES .endr END(lws_lock_start) .previous diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h index 49df148..47b075c 100644 --- a/arch/parisc/include/asm/futex.h +++ b/arch/parisc/include/asm/futex.h @@ -15,7 +15,7 @@ static inline void _futex_spin_lock_irqsave(u32 __user *uaddr, unsigned long int *flags) { extern u32 lws_lock_start[]; - long index = ((long)uaddr & 0xf0) >> 2; + long index = (((long)uaddr & 0xf0) >> 4) << (L1_CACHE_SHIFT-2); arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index]; local_irq_save(*flags); arch_spin_lock(s); @@ -25,7 +25,7 @@ static inline void _futex_spin_unlock_irqrestore(u32 __user *uaddr, unsigned long int *flags) { extern u32 lws_lock_start[]; - long index = ((long)uaddr & 0xf0) >> 2; + long index = (((long)uaddr & 0xf0) >> 4) << (L1_CACHE_SHIFT-2); arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index]; arch_spin_unlock(s); local_irq_restore(*flags);