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authorTony Luck <tony.luck@intel.com>2009-09-25 08:42:16 -0700
committerTony Luck <tony.luck@intel.com>2009-09-25 08:42:16 -0700
commit2c86963b093c1a0887dfc6b32c6e5ea3a80f2922 (patch)
treed1ed58dd0a644dd670e3724a575112fedd4b4250 /arch/ia64/kernel
parent53cddfcc0e760d2b364878b6dadbd0c6d087cfae (diff)
downloadop-kernel-dev-2c86963b093c1a0887dfc6b32c6e5ea3a80f2922.zip
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[IA64] implement ticket locks for Itanium
Back in January 2008 Nick Piggin implemented "ticket" spinlocks for X86 (See commit 314cdbefd1fd0a7acf3780e9628465b77ea6a836). IA64 implementation has a couple of differences because of the available atomic operations ... e.g. we have no fetchadd2 instruction that operates on a 16-bit quantity so we make ticket locks use a 32-bit word for each of the current ticket and now-serving values. Performance on uncontended locks is about 8% worse than the previous implementation, but this seems a good trade for determinism in the contended case. Performance impact on macro-level benchmarks is in the noise. Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/kernel')
-rw-r--r--arch/ia64/kernel/head.S89
-rw-r--r--arch/ia64/kernel/ia64_ksyms.c20
2 files changed, 0 insertions, 109 deletions
diff --git a/arch/ia64/kernel/head.S b/arch/ia64/kernel/head.S
index 1a6e445..696eff2 100644
--- a/arch/ia64/kernel/head.S
+++ b/arch/ia64/kernel/head.S
@@ -1130,95 +1130,6 @@ SET_REG(b5);
#endif /* CONFIG_IA64_BRL_EMU */
#ifdef CONFIG_SMP
- /*
- * This routine handles spinlock contention. It uses a non-standard calling
- * convention to avoid converting leaf routines into interior routines. Because
- * of this special convention, there are several restrictions:
- *
- * - do not use gp relative variables, this code is called from the kernel
- * and from modules, r1 is undefined.
- * - do not use stacked registers, the caller owns them.
- * - do not use the scratch stack space, the caller owns it.
- * - do not use any registers other than the ones listed below
- *
- * Inputs:
- * ar.pfs - saved CFM of caller
- * ar.ccv - 0 (and available for use)
- * r27 - flags from spin_lock_irqsave or 0. Must be preserved.
- * r28 - available for use.
- * r29 - available for use.
- * r30 - available for use.
- * r31 - address of lock, available for use.
- * b6 - return address
- * p14 - available for use.
- * p15 - used to track flag status.
- *
- * If you patch this code to use more registers, do not forget to update
- * the clobber lists for spin_lock() in arch/ia64/include/asm/spinlock.h.
- */
-
-#if (__GNUC__ == 3 && __GNUC_MINOR__ < 3)
-
-GLOBAL_ENTRY(ia64_spinlock_contention_pre3_4)
- .prologue
- .save ar.pfs, r0 // this code effectively has a zero frame size
- .save rp, r28
- .body
- nop 0
- tbit.nz p15,p0=r27,IA64_PSR_I_BIT
- .restore sp // pop existing prologue after next insn
- mov b6 = r28
- .prologue
- .save ar.pfs, r0
- .altrp b6
- .body
- ;;
-(p15) ssm psr.i // reenable interrupts if they were on
- // DavidM says that srlz.d is slow and is not required in this case
-.wait:
- // exponential backoff, kdb, lockmeter etc. go in here
- hint @pause
- ld4 r30=[r31] // don't use ld4.bias; if it's contended, we won't write the word
- nop 0
- ;;
- cmp4.ne p14,p0=r30,r0
-(p14) br.cond.sptk.few .wait
-(p15) rsm psr.i // disable interrupts if we reenabled them
- br.cond.sptk.few b6 // lock is now free, try to acquire
- .global ia64_spinlock_contention_pre3_4_end // for kernprof
-ia64_spinlock_contention_pre3_4_end:
-END(ia64_spinlock_contention_pre3_4)
-
-#else
-
-GLOBAL_ENTRY(ia64_spinlock_contention)
- .prologue
- .altrp b6
- .body
- tbit.nz p15,p0=r27,IA64_PSR_I_BIT
- ;;
-.wait:
-(p15) ssm psr.i // reenable interrupts if they were on
- // DavidM says that srlz.d is slow and is not required in this case
-.wait2:
- // exponential backoff, kdb, lockmeter etc. go in here
- hint @pause
- ld4 r30=[r31] // don't use ld4.bias; if it's contended, we won't write the word
- ;;
- cmp4.ne p14,p0=r30,r0
- mov r30 = 1
-(p14) br.cond.sptk.few .wait2
-(p15) rsm psr.i // disable interrupts if we reenabled them
- ;;
- cmpxchg4.acq r30=[r31], r30, ar.ccv
- ;;
- cmp4.ne p14,p0=r0,r30
-(p14) br.cond.sptk.few .wait
-
- br.ret.sptk.many b6 // lock is now taken
-END(ia64_spinlock_contention)
-
-#endif
#ifdef CONFIG_HOTPLUG_CPU
GLOBAL_ENTRY(ia64_jump_to_sal)
diff --git a/arch/ia64/kernel/ia64_ksyms.c b/arch/ia64/kernel/ia64_ksyms.c
index 8ebccb5..14d39e3 100644
--- a/arch/ia64/kernel/ia64_ksyms.c
+++ b/arch/ia64/kernel/ia64_ksyms.c
@@ -84,26 +84,6 @@ EXPORT_SYMBOL(ia64_save_scratch_fpregs);
#include <asm/unwind.h>
EXPORT_SYMBOL(unw_init_running);
-#ifdef ASM_SUPPORTED
-# ifdef CONFIG_SMP
-# if (__GNUC__ == 3 && __GNUC_MINOR__ < 3)
-/*
- * This is not a normal routine and we don't want a function descriptor for it, so we use
- * a fake declaration here.
- */
-extern char ia64_spinlock_contention_pre3_4;
-EXPORT_SYMBOL(ia64_spinlock_contention_pre3_4);
-# else
-/*
- * This is not a normal routine and we don't want a function descriptor for it, so we use
- * a fake declaration here.
- */
-extern char ia64_spinlock_contention;
-EXPORT_SYMBOL(ia64_spinlock_contention);
-# endif
-# endif
-#endif
-
#if defined(CONFIG_IA64_ESI) || defined(CONFIG_IA64_ESI_MODULE)
extern void esi_call_phys (void);
EXPORT_SYMBOL_GPL(esi_call_phys);
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