Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757215Ab1E3Ond (ORCPT ); Mon, 30 May 2011 10:43:33 -0400 Received: from ch1ehsobe003.messaging.microsoft.com ([216.32.181.183]:44651 "EHLO CH1EHSOBE015.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751687Ab1E3Onb (ORCPT ); Mon, 30 May 2011 10:43:31 -0400 X-SpamScore: -12 X-BigFish: VPS-12(zz4015L1432N98dKzz1202hzz8275bhz32i668h839h61h) X-Spam-TCS-SCL: 0:0 X-Forefront-Antispam-Report: CIP:163.181.249.108;KIP:(null);UIP:(null);IPVD:NLI;H:ausb3twp01.amd.com;RD:none;EFVD:NLI X-WSS-ID: 0LM0JKD-01-0Q7-02 X-M-MSG: Date: Mon, 30 May 2011 16:43:24 +0200 From: Robert Richter To: Ingo Molnar CC: "linux-kernel@vger.kernel.org" , "oprofile-list@lists.sourceforge.net" , Peter Zijlstra Subject: [PATCH] oprofile, x86: Add comments to IBS LVT offset initialization Message-ID: <20110530144324.GM20052@erda.amd.com> References: <20110526133948.GX20052@erda.amd.com> <20110527122301.GA32754@elte.hu> <20110530100039.GB20052@erda.amd.com> <20110530100956.GA17821@elte.hu> <20110530101619.GC20052@erda.amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20110530101619.GC20052@erda.amd.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginatorOrg: amd.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2908 Lines: 92 (resent with modified subject) On 30.05.11 12:16:19, Robert Richter wrote: > On 30.05.11 06:09:56, Ingo Molnar wrote: > > The way IBS is set up is not very obvious and atypical of existing > > preempt_*() patters. Might be worth adding a comment to the > > preempt_disable(), to unconfuse unsuspecting readers who are > > wondering about its oddness? > > Yes, will add some comments. Ingo, please see below and apply the patch to tip, if it makes sense to you. Thanks, -Robert >From cbf74cea070fa1f705de4712e25d9e56ae6543c7 Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Mon, 30 May 2011 16:31:11 +0200 Subject: [PATCH] oprofile, x86: Add comments to IBS LVT offset initialization Adding a comment in the code as IBS LVT setup is not obvious at all ... Signed-off-by: Robert Richter --- arch/x86/kernel/apic/apic.c | 3 ++- arch/x86/oprofile/op_model_amd.c | 13 +++++++++---- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index fabf01e..a0bf78a 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -390,7 +390,8 @@ static unsigned int reserve_eilvt_offset(int offset, unsigned int new) /* * If mask=1, the LVT entry does not generate interrupts while mask=0 - * enables the vector. See also the BKDGs. + * enables the vector. See also the BKDGs. Must be called with + * preemption disabled. */ int setup_APIC_eilvt(u8 offset, u8 vector, u8 msg_type, u8 mask) diff --git a/arch/x86/oprofile/op_model_amd.c b/arch/x86/oprofile/op_model_amd.c index 9fd8a56..9cbb710 100644 --- a/arch/x86/oprofile/op_model_amd.c +++ b/arch/x86/oprofile/op_model_amd.c @@ -609,16 +609,21 @@ static int setup_ibs_ctl(int ibs_eilvt_off) return 0; } +/* + * This runs only on the current cpu. We try to find an LVT offset and + * setup the local APIC. For this we must disable preemption. On + * success we initialize all nodes with this offset. This updates then + * the offset in the IBS_CTL per-node msr. The per-core APIC setup of + * the IBS interrupt vector is called from op_amd_setup_ctrs()/op_- + * amd_cpu_shutdown() using the new offset. + */ static int force_ibs_eilvt_setup(void) { int offset; int ret; - /* - * find the next free available EILVT entry, skip offset 0, - * pin search to this cpu - */ preempt_disable(); + /* find the next free available EILVT entry, skip offset 0 */ for (offset = 1; offset < APIC_EILVT_NR_MAX; offset++) { if (get_eilvt(offset)) break; -- 1.7.5.rc3 -- Advanced Micro Devices, Inc. Operating System Research Center -- 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/