Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758968Ab2JKREy (ORCPT ); Thu, 11 Oct 2012 13:04:54 -0400 Received: from usindpps06.hds.com ([207.126.252.19]:35326 "EHLO usindpps06.hds.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758941Ab2JKREw convert rfc822-to-8bit (ORCPT ); Thu, 11 Oct 2012 13:04:52 -0400 From: Seiji Aguchi To: "H. Peter Anvin" , Steven Rostedt CC: "Thomas Gleixner (tglx@linutronix.de)" , "linux-kernel@vger.kernel.org" , "'mingo@elte.hu' (mingo@elte.hu)" , "x86@kernel.org" , "dle-develop@lists.sourceforge.net" , Satoru Moriya Subject: RE: [PATCH v4] trace,x86: add x86 irq vector tracepoints Thread-Topic: [PATCH v4] trace,x86: add x86 irq vector tracepoints Thread-Index: Ac2YWrA+n8Wn2uRQSgKoDvfneAuZiQClgnuAAIOLIPAAEMXIAADi3wmQAJXsDgAAFQlugAAFpDiAAExo5wAAWdCkMA== Date: Thu, 11 Oct 2012 17:04:03 +0000 Message-ID: References: <50612729.2080307@zytor.com> <50650A7E.90807@zytor.com> <1349446428.6755.56.camel@gandalf.local.home> <506F7849.2080805@zytor.com> <1349492261.6755.87.camel@gandalf.local.home> <50719EEC.7090302@zytor.com> In-Reply-To: <50719EEC.7090302@zytor.com> Accept-Language: ja-JP, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.74.43.113] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.7.7855,1.0.431,0.0.0000 definitions=2012-10-11_05:2012-10-11,2012-10-11,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_policy_notspam policy=outbound_policy score=0 spamscore=0 ipscore=0 suspectscore=1 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=6.0.2-1203120001 definitions=main-1210110163 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1268 Lines: 29 > > > > I didn't say anything magic, but a table of pointers that are very > > critical for the system running. Should we implement it with a single > > switch, like we discussed in San Diego to do with the system call table? > > > > That is, have a "normal" table, and a "trace" table. The trace table > > points to functions that have tracepoints. The first enabler of > > tracing switches the table to use the tracepoints, and the last > > disabler switches it back? > > > > That is certainly a reasonable implementation option. It is slightly less usable than it is for system calls, though, because the vectors in > the IDTs are somewhat scrambled and so you can't just do an indirect jump to the original vector content. This does get messy > because you also want to preserve registers... > Peter, Steven, Thank you for explaining the reason why you think a time penalty should be zero and discussing its implementation. I will update my patch so that a time penalty makes zero and submit it shortly. Seiji -- 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/