@@ -1,8 +1,6 @@
DEF_HELPER_FLAGS_4(cc_compute_all, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int)
DEF_HELPER_FLAGS_4(cc_compute_c, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int)
-DEF_HELPER_0(lock, void)
-DEF_HELPER_0(unlock, void)
DEF_HELPER_3(write_eflags, void, env, tl, i32)
DEF_HELPER_1(read_eflags, tl, env)
DEF_HELPER_2(divb_AL, void, env, tl)
@@ -23,39 +23,6 @@
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"
-/* broken thread support */
-
-#if defined(CONFIG_USER_ONLY)
-QemuMutex global_cpu_lock;
-
-void helper_lock(void)
-{
- qemu_mutex_lock(&global_cpu_lock);
-}
-
-void helper_unlock(void)
-{
- qemu_mutex_unlock(&global_cpu_lock);
-}
-
-void helper_lock_init(void)
-{
- qemu_mutex_init(&global_cpu_lock);
-}
-#else
-void helper_lock(void)
-{
-}
-
-void helper_unlock(void)
-{
-}
-
-void helper_lock_init(void)
-{
-}
-#endif
-
#define GEN_CMPXCHG_HELPER(NAME) \
target_ulong glue(helper_, NAME)(CPUX86State *env, target_ulong addr, \
target_ulong old, target_ulong new) \
@@ -4636,10 +4636,6 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
s->aflag = aflag;
s->dflag = dflag;
- /* lock generation */
- if (prefixes & PREFIX_LOCK)
- gen_helper_lock();
-
/* now check op code */
reswitch:
switch(b) {
@@ -8304,20 +8300,11 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
default:
goto unknown_op;
}
- /* lock generation */
- if (s->prefix & PREFIX_LOCK)
- gen_helper_unlock();
return s->pc;
illegal_op:
- if (s->prefix & PREFIX_LOCK)
- gen_helper_unlock();
- /* XXX: ensure that no lock was generated */
gen_illegal_opcode(s);
return s->pc;
unknown_op:
- if (s->prefix & PREFIX_LOCK)
- gen_helper_unlock();
- /* XXX: ensure that no lock was generated */
gen_unknown_opcode(env, s);
return s->pc;
}
@@ -8409,8 +8396,6 @@ void tcg_x86_init(void)
offsetof(CPUX86State, bnd_regs[i].ub),
bnd_regu_names[i]);
}
-
- helper_lock_init();
}
/* generate intermediate code for basic block 'tb'. */
It's been superseded by the atomic helpers. The use of the atomic helpers provides a significant performance and scalability improvement. Below is the result of running the atomic_add-test microbenchmark with: $ x86_64-linux-user/qemu-x86_64 tests/atomic_add-bench -o 5000000 -r $r -n $n , where $n is the number of threads and $r is the allowed range for the additions. The scenarios measured are: - atomic: implements x86' ADDL with the atomic_add helper (i.e. this patchset) - cmpxchg: implement x86' ADDL with a TCG loop using the cmpxchg helper - master: before this patchset Results sorted in ascending range, i.e. descending degree of contention. Y axis is Throughput in Mops/s. Tests are run on an AMD machine with 64 Opteron 6376 cores. atomic_add-bench: 5000000 ops/thread, [0,1] range 25 ++---------+----------+---------+----------+----------+----------+---++ + atomic +-E--+ + + + + + | |cmpxchg +-H--+ | 20 +Emaster +-N--+ ++ || | |++ | || | 15 +++ ++ |N| | |+| | 10 ++| ++ |+|+ | | | -+E+------ +++ ---+E+------+E+------+E+-----+E+------+E| |+E+E+- +++ +E+------+E+-- | 5 ++|+ ++ |+N+H+--- +++ | ++++N+--+H++----+++ + +++ --++H+------+H+------+H++----+H+---+--- | 0 ++---------+-----H----+---H-----+----------+----------+----------+---H+ 0 10 20 30 40 50 60 Number of threads atomic_add-bench: 5000000 ops/thread, [0,2] range 25 ++---------+----------+---------+----------+----------+----------+---++ ++atomic +-E--+ + + + + + | |cmpxchg +-H--+ | 20 ++master +-N--+ ++ |E| | |++ | ||E | 15 ++| ++ |N|| | |+|| ---+E+------+E+-----+E+------+E| 10 ++| | ---+E+------+E+-----+E+--- +++ +++ ||H+E+--+E+-- | |+++++ | | || | 5 ++|+H+-- +++ ++ |+N+ - ---+H+------+H+------ | + +N+--+H++----+H+---+--+H+----++H+--- + + +H+---+--+H| 0 ++---------+----------+---------+----------+----------+----------+---++ 0 10 20 30 40 50 60 Number of threads atomic_add-bench: 5000000 ops/thread, [0,8] range 40 ++---------+----------+---------+----------+----------+----------+---++ ++atomic +-E--+ + + + + + | 35 +cmpxchg +-H--+ ++ | master +-N--+ ---+E+------+E+------+E+-----+E+------+E| 30 ++| ---+E+-- +++ ++ | | -+E+--- | 25 ++E ---- +++ ++ |+++++ -+E+ | 20 +E+ E-- +++ ++ |H|+++ | |+| +H+------- | 15 ++H+ ---+++ +H+------ ++ |N++H+-- +++--- +H+------++| 10 ++ +++ - +++ ---+H+ +++ +H+ | | +H+-----+H+------+H+-- | 5 ++| +++ ++ ++N+N+--+N++ + + + + + | 0 ++---------+----------+---------+----------+----------+----------+---++ 0 10 20 30 40 50 60 Number of threads atomic_add-bench: 5000000 ops/thread, [0,128] range 160 ++---------+---------+----------+---------+----------+----------+---++ + atomic +-E--+ + + + + + | 140 +cmpxchg +-H--+ +++ +++ ++ | master +-N--+ E--------E------+E+------++| 120 ++ --| | +++ E+ | -- +++ +++ ++| 100 ++ - ++ | +++- +++ ++| 80 ++ -+E+ -+H+------+H+------H--------++ | ---- ---- +++ H| | ---+E+-----+E+- ---+H+ ++| 60 ++ +E+--- +++ ---+H+--- ++ | --+++ ---+H+-- | 40 ++ +E+-+H+--- ++ | +H+ | 20 +EE+ ++ +N+ + + + + + + | 0 ++N-N---N--+---------+----------+---------+----------+----------+---++ 0 10 20 30 40 50 60 Number of threads atomic_add-bench: 5000000 ops/thread, [0,1024] range 350 ++---------+---------+----------+---------+----------+----------+---++ + atomic +-E--+ + + + + + | 300 +cmpxchg +-H--+ +++ | master +-N--+ +++ || | +++ | ----E| 250 ++ | ----E---- ++ | ----E--- | ---+H| 200 ++ -+E+--- +++ ---+H+--- ++ | ---- -+H+-- | | +E+ +++ ---- +++ | 150 ++ ---+++ ---+H+- ++ | --- -+H+-- | 100 ++ ---+E+ ---- +++ ++ | +++ ---+E+-----+H+- | | -+E+------+H+-- | 50 ++ +E+ ++ +EE+ + + + + + + | 0 ++N-N---N--+---------+----------+---------+----------+----------+---++ 0 10 20 30 40 50 60 Number of threads hi-res: http://imgur.com/a/fMRmq For master I stopped measuring master after 8 threads, because there is little point in measuring the well-known performance collapse of a contended lock. Note that using atomic helpers instead of cmpxchg is not only more performant (when the host implements natively the same atomics, as is in this case); it also simplifies the necessary TCG/helper code of the implementation. Compare the difference between the atomic and cmpxchg implementations: case OP_ADDL: if (s1->prefix & PREFIX_LOCK) { - gen_atomic_add_fetch(cpu_T0, cpu_A0, cpu_T1, ot); + TCGv t0, t1, t2, a0; + TCGLabel *retry; + + t0 = tcg_temp_local_new(); + t1 = tcg_temp_local_new(); + t2 = tcg_temp_local_new(); + a0 = tcg_temp_local_new(); + retry = gen_new_label(); + + tcg_gen_mov_tl(a0, cpu_A0); + tcg_gen_mov_tl(t1, cpu_T1); + gen_set_label(retry); + gen_op_ld_v(s1, ot, cpu_T0, a0); + tcg_gen_add_tl(t2, cpu_T0, t1); + gen_cmpxchg(t0, a0, cpu_T0, t2, ot); + tcg_gen_brcond_tl(TCG_COND_NE, t0, cpu_T0, retry); + + tcg_gen_mov_tl(cpu_T0, t2); + tcg_gen_mov_tl(cpu_T1, t1); + + tcg_temp_free(t0); + tcg_temp_free(t1); + tcg_temp_free(t2); + tcg_temp_free(a0); } else { Signed-off-by: Emilio G. Cota <cota@braap.org> --- target-i386/helper.h | 2 -- target-i386/mem_helper.c | 33 --------------------------------- target-i386/translate.c | 15 --------------- 3 files changed, 50 deletions(-)