Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755095AbaF3IvT (ORCPT ); Mon, 30 Jun 2014 04:51:19 -0400 Received: from mga02.intel.com ([134.134.136.20]:53396 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755002AbaF3IvN (ORCPT ); Mon, 30 Jun 2014 04:51:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,573,1400050800"; d="scan'208";a="536450993" From: "Yan, Zheng" To: linux-kernel@vger.kernel.org Cc: a.p.zijlstra@chello.nl, mingo@kernel.org, acme@infradead.org, eranian@google.com, andi@firstfloor.org, "Yan, Zheng" Subject: [PATCH V4 06/16] perf, core: always switch pmu specific data during context switch Date: Mon, 30 Jun 2014 16:50:43 +0800 Message-Id: <1404118253-19532-7-git-send-email-zheng.z.yan@intel.com> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1404118253-19532-1-git-send-email-zheng.z.yan@intel.com> References: <1404118253-19532-1-git-send-email-zheng.z.yan@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If two tasks were both forked from the same parent task, Events in their perf task contexts can be the same. Perf core may leave out switching the perf event contexts. Previous patch inroduces pmu specific data. The data is for saving the LBR stack, it is task specific. So we need to switch the data even when context switch is optimized out. Signed-off-by: Yan, Zheng --- kernel/events/core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 9f35d64..a856813 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2339,6 +2339,7 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn, raw_spin_lock(&ctx->lock); raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING); if (context_equiv(ctx, next_ctx)) { + void *ctx_data; /* * XXX do we need a memory barrier of sorts * wrt to rcu_dereference() of perf_event_ctxp @@ -2347,6 +2348,11 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn, next->perf_event_ctxp[ctxn] = ctx; ctx->task = next; next_ctx->task = task; + + ctx_data = next_ctx->task_ctx_data; + next_ctx->task_ctx_data = ctx->task_ctx_data; + ctx->task_ctx_data = ctx_data; + do_switch = 0; perf_event_sync_stat(ctx, next_ctx); -- 1.9.0 -- 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/