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Cacheline demote to improve performance #11101

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Merged
merged 1 commit into from
May 15, 2023
Merged

Cacheline demote to improve performance #11101

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11 changes: 11 additions & 0 deletions Zend/zend_cpuinfo.h
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Original file line number Diff line number Diff line change
Expand Up @@ -258,4 +258,15 @@ static inline int zend_cpu_supports_pclmul(void) {
}
#endif

/* __builtin_cpu_supports has cldemote from gcc11 */
#if PHP_HAVE_BUILTIN_CPU_SUPPORTS && defined(__GNUC__) && (ZEND_GCC_VERSION >= 11000)
ZEND_NO_SANITIZE_ADDRESS
static inline int zend_cpu_supports_cldemote(void) {
#if PHP_HAVE_BUILTIN_CPU_INIT
__builtin_cpu_init();
#endif
return __builtin_cpu_supports("cldemote");
}
#endif

#endif
35 changes: 35 additions & 0 deletions ext/opcache/jit/zend_jit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -144,6 +144,31 @@ static zend_jit_trace_info *zend_jit_get_current_trace_info(void);
static uint32_t zend_jit_trace_find_exit_point(const void* addr);
#endif

#if ZEND_JIT_TARGET_X86 && defined(__linux__)
# if PHP_HAVE_BUILTIN_CPU_SUPPORTS && defined(__GNUC__) && (ZEND_GCC_VERSION >= 11000)
# define ZEND_JIT_SUPPORT_CLDEMOTE 1
# else
# define ZEND_JIT_SUPPORT_CLDEMOTE 0
# endif
#endif

#if ZEND_JIT_SUPPORT_CLDEMOTE
#include <immintrin.h>
#pragma GCC push_options
#pragma GCC target("cldemote")
// check cldemote by CPUID when JIT startup
static int cpu_support_cldemote = 0;
static inline void shared_cacheline_demote(uintptr_t start, size_t size) {
uintptr_t cache_line_base = start & ~0x3F;
do {
_cldemote((void *)cache_line_base);
// next cacheline start size
cache_line_base += 64;
} while (cache_line_base < start + size);
}
#pragma GCC pop_options
#endif

static int zend_jit_assign_to_variable(dasm_State **Dst,
const zend_op *opline,
zend_jit_addr var_use_addr,
Expand Down Expand Up @@ -973,6 +998,12 @@ static void *dasm_link_and_encode(dasm_State **dasm_state,

/* flush the hardware I-cache */
JIT_CACHE_FLUSH(entry, entry + size);
/* hint to the hardware to push out the cache line that contains the linear address */
#if ZEND_JIT_SUPPORT_CLDEMOTE
if (cpu_support_cldemote && JIT_G(trigger) == ZEND_JIT_ON_HOT_TRACE) {
shared_cacheline_demote((uintptr_t)entry, size);
}
#endif
Comment on lines +1001 to +1006
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What is the reason to do CLDEMOTE only for TRACEs?

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What is the reason to do CLDEMOTE only for TRACEs?

You mentioned that Function JIT may produce more than 10M of code at a single request and CLDEMOTE takes time. So we support tracing JIT.


if (trace_num) {
zend_jit_trace_add_code(entry, dasm_getpclabel(dasm_state, 1));
Expand Down Expand Up @@ -4901,6 +4932,10 @@ ZEND_EXT_API int zend_jit_startup(void *buf, size_t size, bool reattached)
zend_jit_gdb_init();
#endif

#if ZEND_JIT_SUPPORT_CLDEMOTE
cpu_support_cldemote = zend_cpu_supports_cldemote();
#endif

#ifdef HAVE_PTHREAD_JIT_WRITE_PROTECT_NP
zend_write_protect = pthread_jit_write_protect_supported_np();
#endif
Expand Down