[erlang-bugs] hipe_mfait_lock
Mikael Pettersson
mikpelinux@REDACTED
Mon Feb 23 19:34:20 CET 2015
Louis-Philippe Gauthier writes:
> Hi Mikael,
> I got a bit excited and tried it right away. Seems to fix my contention
> issue on hipe_mfait_lock.
>
> Here's the new lock count output (hipe_mfait_lock is not there!):
>
> https://gist.github.com/lpgauth/e85efa59b96726af235d
>
> Thanks,
> LP
Thanks for confirming that it had the intended effect.
I've sent OTP a pull request for it.
/Mikael
> On Mon, Feb 23, 2015 at 9:28 AM, Louis-Philippe Gauthier <
> louis-philippe.gauthier@REDACTED> wrote:
>
> > Hi Mikael,
> > Awesome work, I'll give the patch a try this week.
> >
> > Thanks,
> > LP
> >
> > On Mon, Feb 23, 2015 at 6:30 AM, Mikael Pettersson <mikpelinux@REDACTED>
> > wrote:
> >
> >> Louis-Philippe Gauthier writes:
> >> > Hi Sverker,
> >> > That's not a bad idea, I'll try that approach!
> >> >
> >> > Thanks,
> >> > LP
> >> >
> >> > On Thu, Jan 15, 2015 at 12:27 AM, Sverker Eriksson <
> >> > sverker.eriksson@REDACTED> wrote:
> >> >
> >> > > One quite simple improvement is to change the hipe_mfait_lock to be
> >> a
> >> > > read-write mutex (erts_smp_rwmtx_t).
> >> > > And then do read-lock at lookup and exclusive write-lock only when
> >> > > inserting a new entry in the table.
> >> > >
> >> > > I don't think that requires much knowledge about the VM to pull off
> >> ;-) .
> >> > >
> >> > > /Sverker, Erlang/OTP
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > On 01/14/2015 12:34 AM, Louis-Philippe Gauthier wrote:
> >> > >
> >> > > Hi erlang-bugs,
> >> > > I couple of months ago I tried running our full application using
> >> HiPE. I
> >> > > ran into several issues, some manageable, some not... The most
> >> problematic
> >> > > issue was due to locking, specifically, the hipe_mfait_lock (you can
> >> see
> >> > > the lock counter output in the gist bellow).
> >> > > https://gist.github.com/lpgauth/2b3220f4bceeed6f62d0
> >> > >
> >> > > Looking at the code it's obvious that this is a known problem... the
> >> > > following comment was added when the lock was added in 2010.
> >> > >
> >> > > "XXX: Redesign apply et al to avoid those updates."
> >> https://github.com/erlang/otp/blob/maint/erts/emulator/hipe/hipe_bif0.c#L1218
> >> > >
> >> > > Unfortunately, I'm don't know the runtime enough to start patching
> >> it... so
> >> > > instead I'm reporting it.
> >>
> >> Please try the attached patch (against 17.4, should apply to older
> >> versions too by I haven't checked), and let me know if it makes a
> >> noticeable improvement to your use case.
> >>
> >> Run-time apply:s now do their lookups using a shared read-lock, and
> >> only if their lookups fail do they re-lock with an exclusive write-lock
> >> in order to insert new data. Module loading functions always take
> >> exclusive locks, which matches the current behaviour.
> >>
> >> /Mikael
> >>
> >>
> >> --- otp_src_17.4/erts/emulator/hipe/hipe_bif0.c.~1~ 2014-12-09
> >> 21:11:07.000000000 +0100
> >> +++ otp_src_17.4/erts/emulator/hipe/hipe_bif0.c 2015-02-22
> >> 21:32:55.361884741 +0100
> >> @@ -1217,22 +1217,32 @@ static struct {
> >> * they create a new stub for the mfa, which forces locking.
> >> * XXX: Redesign apply et al to avoid those updates.
> >> */
> >> - erts_smp_mtx_t lock;
> >> + erts_smp_rwmtx_t lock;
> >> } hipe_mfa_info_table;
> >>
> >> static inline void hipe_mfa_info_table_init_lock(void)
> >> {
> >> - erts_smp_mtx_init(&hipe_mfa_info_table.lock, "hipe_mfait_lock");
> >> + erts_smp_rwmtx_init(&hipe_mfa_info_table.lock, "hipe_mfait_lock");
> >> }
> >>
> >> -static inline void hipe_mfa_info_table_lock(void)
> >> +static inline void hipe_mfa_info_table_rlock(void)
> >> {
> >> - erts_smp_mtx_lock(&hipe_mfa_info_table.lock);
> >> + erts_smp_rwmtx_rlock(&hipe_mfa_info_table.lock);
> >> }
> >>
> >> -static inline void hipe_mfa_info_table_unlock(void)
> >> +static inline void hipe_mfa_info_table_runlock(void)
> >> {
> >> - erts_smp_mtx_unlock(&hipe_mfa_info_table.lock);
> >> + erts_smp_rwmtx_runlock(&hipe_mfa_info_table.lock);
> >> +}
> >> +
> >> +static inline void hipe_mfa_info_table_rwlock(void)
> >> +{
> >> + erts_smp_rwmtx_rwlock(&hipe_mfa_info_table.lock);
> >> +}
> >> +
> >> +static inline void hipe_mfa_info_table_rwunlock(void)
> >> +{
> >> + erts_smp_rwmtx_rwunlock(&hipe_mfa_info_table.lock);
> >> }
> >>
> >> #define HIPE_MFA_HASH(M,F,A) ((M) * (F) + (A))
> >> @@ -1333,6 +1343,7 @@ void *hipe_mfa_find_na(Eterm m, Eterm f,
> >> }
> >> #endif
> >>
> >> +/* PRE: called with write lock held */
> >> static struct hipe_mfa_info *hipe_mfa_info_table_put_locked(Eterm m,
> >> Eterm f, unsigned int arity)
> >> {
> >> unsigned long h;
> >> @@ -1362,7 +1373,7 @@ static void hipe_mfa_set_na(Eterm m, Ete
> >> {
> >> struct hipe_mfa_info *p;
> >>
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> p = hipe_mfa_info_table_put_locked(m, f, arity);
> >> #ifdef DEBUG_LINKER
> >> printf("%s: ", __FUNCTION__);
> >> @@ -1372,7 +1383,7 @@ static void hipe_mfa_set_na(Eterm m, Ete
> >> p->local_address = address;
> >> if (is_exported)
> >> p->remote_address = address;
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> }
> >>
> >> #if defined(__powerpc__) || defined(__ppc__) || defined(__powerpc64__)
> >> || defined(__arm__)
> >> @@ -1381,10 +1392,10 @@ void *hipe_mfa_get_trampoline(Eterm m, E
> >> struct hipe_mfa_info *p;
> >> void *trampoline;
> >>
> >> - hipe_mfa_info_table_lock();
> >> - p = hipe_mfa_info_table_put_locked(m, f, arity);
> >> - trampoline = p->trampoline;
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rlock();
> >> + p = hipe_mfa_info_table_get_locked(m, f, arity);
> >> + trampoline = p ? p->trampoline : NULL;
> >> + hipe_mfa_info_table_runlock();
> >> return trampoline;
> >> }
> >>
> >> @@ -1392,10 +1403,10 @@ void hipe_mfa_set_trampoline(Eterm m, Et
> >> {
> >> struct hipe_mfa_info *p;
> >>
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> p = hipe_mfa_info_table_put_locked(m, f, arity);
> >> p->trampoline = trampoline;
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> }
> >> #endif
> >>
> >> @@ -1426,7 +1437,7 @@ BIF_RETTYPE hipe_bifs_invalidate_funinfo
> >> struct mfa mfa;
> >> struct hipe_mfa_info *p;
> >>
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> lst = BIF_ARG_1;
> >> while (is_list(lst)) {
> >> if (!term_to_mfa(CAR(list_val(lst)), &mfa))
> >> @@ -1455,7 +1466,7 @@ BIF_RETTYPE hipe_bifs_invalidate_funinfo
> >> }
> >> }
> >> }
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> if (is_not_nil(lst))
> >> BIF_ERROR(BIF_P, BADARG);
> >> BIF_RET(NIL);
> >> @@ -1469,7 +1480,7 @@ void hipe_mfa_save_orig_beam_op(Eterm mo
> >> orig_beam_op = pc[0];
> >> if (orig_beam_op != BeamOpCode(op_hipe_trap_call_closure) &&
> >> orig_beam_op != BeamOpCode(op_hipe_trap_call)) {
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> p = hipe_mfa_info_table_put_locked(mod, fun, ari);
> >> #ifdef DEBUG_LINKER
> >> printf("%s: ", __FUNCTION__);
> >> @@ -1478,7 +1489,7 @@ void hipe_mfa_save_orig_beam_op(Eterm mo
> >> #endif
> >> p->beam_code = pc;
> >> p->orig_beam_op = orig_beam_op;
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> } else {
> >> #ifdef DEBUG_LINKER
> >> printf("%s: ", __FUNCTION__);
> >> @@ -1505,7 +1516,8 @@ static void *hipe_make_stub(Eterm m, Ete
> >> return StubAddress;
> >> }
> >>
> >> -static void *hipe_get_na_nofail_locked(Eterm m, Eterm f, unsigned int a,
> >> int is_remote)
> >> +/* PRE: called with read or write lock held */
> >> +static void *hipe_get_na_try_locked(Eterm m, Eterm f, unsigned int a,
> >> int is_remote, struct hipe_mfa_info **pp)
> >> {
> >> struct hipe_mfa_info *p;
> >> void *address;
> >> @@ -1523,7 +1535,20 @@ static void *hipe_get_na_nofail_locked(E
> >> address = p->remote_address;
> >> if (address)
> >> return address;
> >> - } else
> >> + }
> >> + /* Caller must take the slow path with the write lock held, but allow
> >> + it to avoid some work if it already holds the write lock. */
> >> + if (pp)
> >> + *pp = p;
> >> + return NULL;
> >> +}
> >> +
> >> +/* PRE: called with write lock held */
> >> +static void *hipe_get_na_slow_locked(Eterm m, Eterm f, unsigned int a,
> >> int is_remote, struct hipe_mfa_info *p)
> >> +{
> >> + void *address;
> >> +
> >> + if (!p)
> >> p = hipe_mfa_info_table_put_locked(m, f, a);
> >> address = hipe_make_stub(m, f, a, is_remote);
> >> /* XXX: how to tell if a BEAM MFA is exported or not? */
> >> @@ -1531,14 +1556,34 @@ static void *hipe_get_na_nofail_locked(E
> >> return address;
> >> }
> >>
> >> +/* PRE: called with write lock held */
> >> +static void *hipe_get_na_nofail_locked(Eterm m, Eterm f, unsigned int a,
> >> int is_remote)
> >> +{
> >> + struct hipe_mfa_info *p /*= NULL*/;
> >> + void *address;
> >> +
> >> + address = hipe_get_na_try_locked(m, f, a, is_remote, &p);
> >> + if (address)
> >> + return address;
> >> +
> >> + address = hipe_get_na_slow_locked(m, f, a, is_remote, p);
> >> + return address;
> >> +}
> >> +
> >> static void *hipe_get_na_nofail(Eterm m, Eterm f, unsigned int a, int
> >> is_remote)
> >> {
> >> - void *p;
> >> + void *address;
> >>
> >> - hipe_mfa_info_table_lock();
> >> - p = hipe_get_na_nofail_locked(m, f, a, is_remote);
> >> - hipe_mfa_info_table_unlock();
> >> - return p;
> >> + hipe_mfa_info_table_rlock();
> >> + address = hipe_get_na_try_locked(m, f, a, is_remote, NULL);
> >> + hipe_mfa_info_table_runlock();
> >> + if (address)
> >> + return address;
> >> +
> >> + hipe_mfa_info_table_rwlock();
> >> + address = hipe_get_na_slow_locked(m, f, a, is_remote, NULL);
> >> + hipe_mfa_info_table_rwunlock();
> >> + return address;
> >> }
> >>
> >> /* used for apply/3 in hipe_mode_switch */
> >> @@ -1617,7 +1662,7 @@ int hipe_find_mfa_from_ra(const void *ra
> >> /* Note about locking: the table is only updated from the
> >> loader, which runs with the rest of the system suspended. */
> >> /* XXX: alas not true; see comment at hipe_mfa_info_table.lock */
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> bucket = hipe_mfa_info_table.bucket;
> >> nrbuckets = 1 << hipe_mfa_info_table.log2size;
> >> mfa = NULL;
> >> @@ -1638,7 +1683,7 @@ int hipe_find_mfa_from_ra(const void *ra
> >> *f = mfa->f;
> >> *a = mfa->a;
> >> }
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> return mfa ? 1 : 0;
> >> }
> >>
> >> @@ -1715,7 +1760,7 @@ BIF_RETTYPE hipe_bifs_add_ref_2(BIF_ALIS
> >> default:
> >> goto badarg;
> >> }
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> callee_mfa = hipe_mfa_info_table_put_locked(callee.mod, callee.fun,
> >> callee.ari);
> >> caller_mfa = hipe_mfa_info_table_put_locked(caller.mod, caller.fun,
> >> caller.ari);
> >>
> >> @@ -1731,7 +1776,7 @@ BIF_RETTYPE hipe_bifs_add_ref_2(BIF_ALIS
> >> ref->flags = flags;
> >> ref->next = callee_mfa->referred_from;
> >> callee_mfa->referred_from = ref;
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >>
> >> BIF_RET(NIL);
> >>
> >> @@ -1751,12 +1796,12 @@ BIF_RETTYPE hipe_bifs_mark_referred_from
> >>
> >> if (!term_to_mfa(BIF_ARG_1, &mfa))
> >> BIF_ERROR(BIF_P, BADARG);
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> p = hipe_mfa_info_table_get_locked(mfa.mod, mfa.fun, mfa.ari);
> >> if (p)
> >> for (ref = p->referred_from; ref != NULL; ref = ref->next)
> >> ref->flags |= REF_FLAG_PENDING_REDIRECT;
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> BIF_RET(NIL);
> >> }
> >>
> >> @@ -1770,7 +1815,7 @@ static void hipe_purge_all_refs(void)
> >> struct hipe_mfa_info **bucket;
> >> unsigned int i, nrbuckets;
> >>
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >>
> >> bucket = hipe_mfa_info_table.bucket;
> >> nrbuckets = 1 << hipe_mfa_info_table.log2size;
> >> @@ -1792,7 +1837,7 @@ static void hipe_purge_all_refs(void)
> >> erts_free(ERTS_ALC_T_HIPE, mfa);
> >> }
> >> }
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> }
> >>
> >> BIF_RETTYPE hipe_bifs_remove_refs_from_1(BIF_ALIST_1)
> >> @@ -1809,7 +1854,7 @@ BIF_RETTYPE hipe_bifs_remove_refs_from_1
> >>
> >> if (!term_to_mfa(BIF_ARG_1, &mfa))
> >> BIF_ERROR(BIF_P, BADARG);
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> caller_mfa = hipe_mfa_info_table_get_locked(mfa.mod, mfa.fun,
> >> mfa.ari);
> >> if (caller_mfa) {
> >> refers_to = caller_mfa->refers_to;
> >> @@ -1840,7 +1885,7 @@ BIF_RETTYPE hipe_bifs_remove_refs_from_1
> >> }
> >> caller_mfa->refers_to = NULL;
> >> }
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> BIF_RET(am_ok);
> >> }
> >>
> >> @@ -1859,7 +1904,7 @@ BIF_RETTYPE hipe_bifs_redirect_referred_
> >>
> >> if (!term_to_mfa(BIF_ARG_1, &mfa))
> >> BIF_ERROR(BIF_P, BADARG);
> >> - hipe_mfa_info_table_lock();
> >> + hipe_mfa_info_table_rwlock();
> >> p = hipe_mfa_info_table_get_locked(mfa.mod, mfa.fun, mfa.ari);
> >> if (p) {
> >> prev = &p->referred_from;
> >> @@ -1890,7 +1935,7 @@ BIF_RETTYPE hipe_bifs_redirect_referred_
> >> }
> >> }
> >> }
> >> - hipe_mfa_info_table_unlock();
> >> + hipe_mfa_info_table_rwunlock();
> >> BIF_RET(NIL);
> >> }
> >>
> >>
> >>
> >
--
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