From owner-freebsd-current@FreeBSD.ORG Thu May 5 23:33:35 2011 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D46FF106566B; Thu, 5 May 2011 23:33:35 +0000 (UTC) (envelope-from davidch@broadcom.com) Received: from MMS3.broadcom.com (mms3.broadcom.com [216.31.210.19]) by mx1.freebsd.org (Postfix) with ESMTP id 8BB1E8FC08; Thu, 5 May 2011 23:33:35 +0000 (UTC) Received: from [10.9.200.131] by MMS3.broadcom.com with ESMTP (Broadcom SMTP Relay (Email Firewall v6.3.2)); Thu, 05 May 2011 16:36:42 -0700 X-Server-Uuid: B55A25B1-5D7D-41F8-BC53-C57E7AD3C201 Received: from IRVEXCHCCR01.corp.ad.broadcom.com ([10.252.49.30]) by IRVEXCHHUB01.corp.ad.broadcom.com ([10.9.200.131]) with mapi; Thu, 5 May 2011 16:33:20 -0700 From: "David Christensen" To: "Artem Belevich" Date: Thu, 5 May 2011 16:33:09 -0700 Thread-Topic: Using Dtrace for Performance Evaluation Thread-Index: AcwLe6p564GarEuHQveBOVBDk2ZjcQAAQ3eA Message-ID: <5D267A3F22FD854F8F48B3D2B523819360D799A517@IRVEXCHCCR01.corp.ad.broadcom.com> References: <5D267A3F22FD854F8F48B3D2B523819360D799A42B@IRVEXCHCCR01.corp.ad.broadcom.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-cr-hashedpuzzle: A7ws B2Nf FL9g F20c GTGz Gxoq Hb3d IsZ0 MJWc NwDG O/7H PBwf Pvrw SZdE T0NZ VykV; 2; YQByAHQAQABmAHIAZQBlAGIAcwBkAC4AbwByAGcAOwBmAHIAZQBlAGIAcwBkAC0AYwB1AHIAcgBlAG4AdABAAGYAcgBlAGUAYgBzAGQALgBvAHIAZwA=; Sosha1_v1; 7; {A9FB8ACA-FC90-408B-9EC0-771981079C02}; ZABhAHYAaQBkAGMAaABAAGIAcgBvAGEAZABjAG8AbQAuAGMAbwBtAA==; Thu, 05 May 2011 23:33:09 GMT; UgBFADoAIABVAHMAaQBuAGcAIABEAHQAcgBhAGMAZQAgAGYAbwByACAAUABlAHIAZgBvAHIAbQBhAG4AYwBlACAARQB2AGEAbAB1AGEAdABpAG8AbgA= x-cr-puzzleid: {A9FB8ACA-FC90-408B-9EC0-771981079C02} acceptlanguage: en-US MIME-Version: 1.0 X-WSS-ID: 61DDEB004NS1501618-01-01 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Cc: "freebsd-current@freebsd.org" Subject: RE: Using Dtrace for Performance Evaluation X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 May 2011 23:33:36 -0000 > > After building dtrace into the kernel and loading the dtraceall > > kernel module, when I load my bxe kernel module and run "dtrace -l" > > to list all supported probes I notice that many functions have an > > entry probe but no exit probe. =A0This effectively prevents me from > > calculating timestamps on "fbt:if_bxe::return" probes. =A0Why am I > > seeing this behavior? >=20 > Tail call optimization could do that to you: > http://en.wikipedia.org/wiki/Tail_call How to disable tail call optimization when building my driver? Dave