Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755271AbZFVR6Y (ORCPT ); Mon, 22 Jun 2009 13:58:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753792AbZFVR6R (ORCPT ); Mon, 22 Jun 2009 13:58:17 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:50704 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753736AbZFVR6Q (ORCPT ); Mon, 22 Jun 2009 13:58:16 -0400 In-Reply-To: <4A3F9062.6000303@renci.org> Subject: Re: [perfmon2] IV.3 - AMD IBS To: Rob Fowler Cc: Andrew Morton , Andi Kleen , Peter Zijlstra , eranian@gmail.com, LKML , Ingo Molnar , Philip Mucci , Paul Mackerras , perfmon2-devel , Thomas Gleixner , Suravee.Suthikulpanit@amd.com X-Mailer: Lotus Notes Release 7.0 HF277 June 21, 2006 Message-ID: From: Maynard Johnson Date: Mon, 22 Jun 2009 12:58:14 -0500 X-MIMETrack: Serialize by Router on d27ml103/27/M/IBM(Release 8.0.2FP1|January 12, 2009) at 06/22/2009 12:58:16 PM MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3354 Lines: 97 Rob Fowler wrote on 06/22/2009 09:08:34 AM: > > > Ingo Molnar wrote: > >> 3/ AMD IBS > >> > >> How is AMD IBS going to be implemented? > >> > >> IBS has two separate sets of registers. One to capture fetch > >> related data and another one to capture instruction execution > >> data. For each, there is one config register but multiple data > >> registers. In each mode, there is a specific sampling period and > >> IBS can interrupt. > >> > >> It looks like you could define two pseudo events or event types > >> and then define a new record_format and read_format. That formats > >> would only be valid for an IBS event. > >> > >> Is that how you intend to support IBS? > > > > That is indeed one of the ways we thought of, not really nice, but > > then, IBS is really weird, what were those AMD engineers thinking > > :-) > > Actually, IBS has roots in DEC's "ProfileMe" for Alpha EV67 and later > processors. Those of us who used it there found it to be an extremely > powerful, low-overhead mechanism for directly collecting information about > how well the micro-architecture is performing. In particular, it can tell > you, not only which instructions take a long time to traverse the pipe, but > it also tells you which instructions delay other instructions and byhow much. > This is extremely valuable if you are either working on instruction scheduling > in a compiler, or are modifying a program to give the compiler the opportunity > to do a good job. > > A core group of engineers who worked on Alpha went on to AMD. > > An unfortunate problem with IBS on AMD is that good support isn't > common in the "mainstream" > open source community. > > Code Analyst from AMD, also involving ex-DEC engineers, is > the only place where it is supported at all decently throughout the > tool chain. > Last time I looked, there was a tweaked version of oprofile underlying CA. > I haven't checked to see whether the tweaks have migrated back into > the oprofile trunk. Yes, IBS on AMD is now supported upstream in mainline, contributed by Suravee Suthikulpanit. -Maynard > > > > > > The point is - weird hardware gets expressed as a ... weird feature > > under perfcounters too. Not all hardware weirdnesses can be > > engineered away. > > > > > ------------------------------------------------------------------------------ > > Are you an open source citizen? Join us for the Open Source Bridge > conference! > > Portland, OR, June 17-19. Two days of sessions, one day of > unconference: $250. > > Need another reason to go? 24-hour hacker lounge. Register today! > > http://ad.doubleclick.net/clk;215844324;13503038;v?http: > //opensourcebridge.org > > _______________________________________________ > > perfmon2-devel mailing list > > perfmon2-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/perfmon2-devel > > -- > Robert J. Fowler > Chief Domain Scientist, HPC > Renaissance Computing Institute > The University of North Carolina at Chapel Hill > 100 Europa Dr, Suite 540 > Chapel Hill, NC 27517 > V: 919.445.9670 > F: 919 445.9669 > rjf@renci.org -- 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/