Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756963AbbEVNda (ORCPT ); Fri, 22 May 2015 09:33:30 -0400 Received: from casper.infradead.org ([85.118.1.10]:49344 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756420AbbEVNdS (ORCPT ); Fri, 22 May 2015 09:33:18 -0400 Message-Id: <20150522133135.545977325@infradead.org> User-Agent: quilt/0.61-1 Date: Fri, 22 May 2015 15:29:08 +0200 From: Peter Zijlstra To: mingo@kernel.org, peterz@infradead.org Cc: vincent.weaver@maine.edu, eranian@google.com, jolsa@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 03/11] perf/x86: Correct local vs remote sibling state References: <20150522132905.416122812@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-pmu-sched-3.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6440 Lines: 224 For some obscure reason the current code accounts the current SMT thread's state on the remote thread and reads the remote's state on the local SMT thread. While internally consistent, and 'correct' its pointless confusion we can do without. Flip them the right way around. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/kernel/cpu/perf_event_intel.c | 79 +++++++++++++-------------------- 1 file changed, 33 insertions(+), 46 deletions(-) --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1903,9 +1903,8 @@ static void intel_start_scheduling(struct cpu_hw_events *cpuc) { struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs; - struct intel_excl_states *xl, *xlo; + struct intel_excl_states *xl; int tid = cpuc->excl_thread_id; - int o_tid = 1 - tid; /* sibling thread */ /* * nothing needed if in group validation mode @@ -1919,7 +1918,6 @@ intel_start_scheduling(struct cpu_hw_eve if (!excl_cntrs) return; - xlo = &excl_cntrs->states[o_tid]; xl = &excl_cntrs->states[tid]; xl->sched_started = true; @@ -1932,18 +1930,17 @@ intel_start_scheduling(struct cpu_hw_eve raw_spin_lock(&excl_cntrs->lock); /* - * save initial state of sibling thread + * Save a copy of our state to work on. */ - memcpy(xlo->init_state, xlo->state, sizeof(xlo->init_state)); + memcpy(xl->init_state, xl->state, sizeof(xl->init_state)); } static void intel_stop_scheduling(struct cpu_hw_events *cpuc) { struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs; - struct intel_excl_states *xl, *xlo; + struct intel_excl_states *xl; int tid = cpuc->excl_thread_id; - int o_tid = 1 - tid; /* sibling thread */ /* * nothing needed if in group validation mode @@ -1956,13 +1953,12 @@ intel_stop_scheduling(struct cpu_hw_even if (!excl_cntrs) return; - xlo = &excl_cntrs->states[o_tid]; xl = &excl_cntrs->states[tid]; /* - * make new sibling thread state visible + * Commit the working state. */ - memcpy(xlo->state, xlo->init_state, sizeof(xlo->state)); + memcpy(xl->state, xl->init_state, sizeof(xl->state)); xl->sched_started = false; /* @@ -1977,10 +1973,9 @@ intel_get_excl_constraints(struct cpu_hw { struct event_constraint *cx; struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs; - struct intel_excl_states *xl, *xlo; - int is_excl, i; + struct intel_excl_states *xlo; int tid = cpuc->excl_thread_id; - int o_tid = 1 - tid; /* alternate */ + int is_excl, i; /* * validating a group does not require @@ -1994,23 +1989,6 @@ intel_get_excl_constraints(struct cpu_hw */ if (!excl_cntrs) return c; - /* - * event requires exclusive counter access - * across HT threads - */ - is_excl = c->flags & PERF_X86_EVENT_EXCL; - if (is_excl && !(event->hw.flags & PERF_X86_EVENT_EXCL_ACCT)) { - event->hw.flags |= PERF_X86_EVENT_EXCL_ACCT; - if (!cpuc->n_excl++) - WRITE_ONCE(excl_cntrs->has_exclusive[tid], 1); - } - - /* - * xl = state of current HT - * xlo = state of sibling HT - */ - xl = &excl_cntrs->states[tid]; - xlo = &excl_cntrs->states[o_tid]; cx = c; @@ -2054,6 +2032,22 @@ intel_get_excl_constraints(struct cpu_hw */ /* + * state of sibling HT + */ + xlo = &excl_cntrs->states[tid ^ 1]; + + /* + * event requires exclusive counter access + * across HT threads + */ + is_excl = c->flags & PERF_X86_EVENT_EXCL; + if (is_excl && !(event->hw.flags & PERF_X86_EVENT_EXCL_ACCT)) { + event->hw.flags |= PERF_X86_EVENT_EXCL_ACCT; + if (!cpuc->n_excl++) + WRITE_ONCE(excl_cntrs->has_exclusive[tid], 1); + } + + /* * Modify static constraint with current dynamic * state of thread * @@ -2067,14 +2061,14 @@ intel_get_excl_constraints(struct cpu_hw * our corresponding counter cannot be used * regardless of our event */ - if (xl->state[i] == INTEL_EXCL_EXCLUSIVE) + if (xlo->state[i] == INTEL_EXCL_EXCLUSIVE) __clear_bit(i, cx->idxmsk); /* * if measuring an exclusive event, sibling * measuring non-exclusive, then counter cannot * be used */ - if (is_excl && xl->state[i] == INTEL_EXCL_SHARED) + if (is_excl && xlo->state[i] == INTEL_EXCL_SHARED) __clear_bit(i, cx->idxmsk); } @@ -2124,10 +2118,9 @@ static void intel_put_excl_constraints(s { struct hw_perf_event *hwc = &event->hw; struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs; - struct intel_excl_states *xlo, *xl; - unsigned long flags = 0; /* keep compiler happy */ int tid = cpuc->excl_thread_id; - int o_tid = 1 - tid; + struct intel_excl_states *xl; + unsigned long flags = 0; /* keep compiler happy */ /* * nothing needed if in group validation mode @@ -2141,7 +2134,6 @@ static void intel_put_excl_constraints(s return; xl = &excl_cntrs->states[tid]; - xlo = &excl_cntrs->states[o_tid]; if (hwc->flags & PERF_X86_EVENT_EXCL_ACCT) { hwc->flags &= ~PERF_X86_EVENT_EXCL_ACCT; if (!--cpuc->n_excl) @@ -2161,7 +2153,7 @@ static void intel_put_excl_constraints(s * counter state as unused now */ if (hwc->idx >= 0) - xlo->state[hwc->idx] = INTEL_EXCL_UNUSED; + xl->state[hwc->idx] = INTEL_EXCL_UNUSED; if (!xl->sched_started) raw_spin_unlock_irqrestore(&excl_cntrs->lock, flags); @@ -2200,16 +2192,12 @@ static void intel_commit_scheduling(stru { struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs; struct event_constraint *c = cpuc->event_constraint[idx]; - struct intel_excl_states *xlo, *xl; + struct intel_excl_states *xl; int tid = cpuc->excl_thread_id; - int o_tid = 1 - tid; - int is_excl; if (cpuc->is_fake || !c) return; - is_excl = c->flags & PERF_X86_EVENT_EXCL; - if (!(c->flags & PERF_X86_EVENT_DYNAMIC)) return; @@ -2219,15 +2207,14 @@ static void intel_commit_scheduling(stru return; xl = &excl_cntrs->states[tid]; - xlo = &excl_cntrs->states[o_tid]; WARN_ON_ONCE(!raw_spin_is_locked(&excl_cntrs->lock)); if (cntr >= 0) { - if (is_excl) - xlo->init_state[cntr] = INTEL_EXCL_EXCLUSIVE; + if (c->flags & PERF_X86_EVENT_EXCL) + xl->init_state[cntr] = INTEL_EXCL_EXCLUSIVE; else - xlo->init_state[cntr] = INTEL_EXCL_SHARED; + xl->init_state[cntr] = INTEL_EXCL_SHARED; } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/