From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29750 invoked by alias); 27 Nov 2012 18:31:08 -0000 Received: (qmail 29644 invoked by uid 22791); 27 Nov 2012 18:31:00 -0000 X-SWARE-Spam-Status: No, hits=-6.5 required=5.0 tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,RCVD_IN_DNSWL_HI,RCVD_IN_HOSTKARMA_W,RP_MATCHES_RCVD,SPF_HELO_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 27 Nov 2012 18:30:52 +0000 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id qARI01A1019764 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 27 Nov 2012 13:00:01 -0500 Received: from host2.jankratochvil.net (ovpn-116-39.ams2.redhat.com [10.36.116.39]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id qARHxusj032530 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Tue, 27 Nov 2012 12:59:59 -0500 Date: Tue, 27 Nov 2012 18:31:00 -0000 From: Jan Kratochvil To: "Metzger, Markus T" Cc: "gdb-patches@sourceware.org" , "markus.t.metzger@gmail.com" , "palves@redhat.com" , "tromey@redhat.com" , "kettenis@gnu.org" Subject: Re: [patch v4 00/13] branch tracing support for Atom Message-ID: <20121127175955.GA8901@host2.jankratochvil.net> References: <1354013351-14791-1-git-send-email-markus.t.metzger@intel.com> <20121127131055.GB22431@host2.jankratochvil.net> <20121127143235.GA31270@host2.jankratochvil.net> <20121127153603.GA1899@host2.jankratochvil.net> <20121127162740.GA4512@host2.jankratochvil.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2012-11/txt/msg00765.txt.bz2 On Tue, 27 Nov 2012 18:30:03 +0100, Metzger, Markus T wrote: > Btrace uses a ring buffer into which the h/w writes from-to records for each > branch. We will only see the tail of the execution trace. OK, I see only 168 entries here. Originally I expected kernel traps and records the buffer each time. arch/x86/ even sets bts_interrupt_threshold, why is the recorded buffer so short? With such short recorded buffer I understand the backtracing feature is not much useful. Although I do not understand why only so few entries got recorded. Thanks, Jan