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Fixes #285: Increase available allocation range in mcode_alloc()

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Change mcode_alloc() so that instead of all execution threads using the
same allocation range of '[target - range/2; target + range / 2]' (where
'range' is the jump range defined by the architecture), make some
threads use the '[target - range; target]' range, and other ones use
'[target; target + range]' based on a PRNG. The patch essentially
doubles the available allocation pool for mcode_alloc() and helps reduce
mmap() scalability issues for multi-threaded applications.
This commit is contained in:
Alexey Kopytov 2017-02-25 17:46:43 +03:00
parent 387d3abff4
commit 60a5e52bf7
3 changed files with 27 additions and 15 deletions
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4
src/lj_jit.h
View File

@ -452,6 +452,10 @@ typedef struct jit_State {
uint32_t penaltyslot; /* Round-robin index into penalty slots. */
uint32_t prngstate; /* PRNG state. */
uintptr_t target; /* target address for mcode_alloc() */
uintptr_t range; /* allocation range for mcode_alloc() */
uintptr_t allocbase; /* allocation base addred for mcode_alloc() */
#ifdef LUAJIT_ENABLE_TABLE_BUMP
RBCHashEntry rbchash[RBCHASH_SLOTS]; /* Reverse bytecode map. */
#endif

21
src/lj_mcode.c
View File

@ -219,18 +219,8 @@ static void mcode_protect(jit_State *J, int prot)
static void *mcode_alloc(jit_State *J, size_t sz)
{
/* Target an address in the static assembler code (64K aligned).
** Try addresses within a distance of target-range/2+1MB..target+range/2-1MB.
** Use half the jump range so every address in the range can reach any other.
*/
#if LJ_TARGET_MIPS
/* Use the middle of the 256MB-aligned region. */
uintptr_t target = ((uintptr_t)(void *)lj_vm_exit_handler &
~(uintptr_t)0x0fffffffu) + 0x08000000u;
#else
uintptr_t target = (uintptr_t)(void *)lj_vm_exit_handler & ~(uintptr_t)0xffff;
#endif
const uintptr_t range = (1u << (LJ_TARGET_JUMPRANGE-1)) - (1u << 21);
/* First try a contiguous area below the last one. */
** Try addresses within a distance of J->allocbase..J->allocbase+J->range.
** First try a contiguous area below the last one. */
uintptr_t hint = J->mcarea ? (uintptr_t)J->mcarea - sz : 0;
int i;
for (i = 0; i < 32; i++) { /* 32 attempts ought to be enough ... */
@ -238,15 +228,16 @@ static void *mcode_alloc(jit_State *J, size_t sz)
void *p = mcode_alloc_at(J, hint, sz, MCPROT_GEN);
if (mcode_validptr(p) &&
((uintptr_t)p + sz - target < range || target - (uintptr_t)p < range))
((uintptr_t)p + sz - J->target < J->range ||
J->target - (uintptr_t)p < J->range))
return p;
if (p) mcode_free(J, p, sz); /* Free badly placed area. */
}
/* Next try probing pseudo-random addresses. */
do {
hint = LJ_PRNG_BITS(J, LJ_TARGET_JUMPRANGE-16) << 16; /* 64K aligned. */
} while (!(hint + sz < range*2));
hint = target + hint - range;
} while (!(hint + sz < J->range));
hint = J->allocbase + hint;
}
lj_trace_err(J, LJ_TRERR_MCODEAL); /* Give up. OS probably ignores hints? */
return NULL;

17
src/lj_state.c
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@ -225,6 +225,23 @@ LUA_API lua_State *lua_newstate(lua_Alloc f, void *ud)
return NULL;
}
L->status = 0;
#if LJ_TARGET_MIPS
/* Use the middle of the 256MB-aligned region. */
uintptr_t target = ((uintptr_t)(void *)lj_vm_exit_handler &
~(uintptr_t)0x0fffffffu) + 0x08000000u;
#else
uintptr_t target = (uintptr_t)(void *)lj_vm_exit_handler & ~(uintptr_t)0xffff;
#endif
uintptr_t range = (1u << LJ_TARGET_JUMPRANGE) - (1u << 21);
uintptr_t allocbase;
if (LJ_PRNG_BITS(G2J(g), 1)) {
allocbase = (target - range > target) ? 0 : target - range;
} else {
allocbase = target;
}
G2J(g)->target = target;
G2J(g)->range = range;
G2J(g)->allocbase = allocbase;
return L;
}