From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758970AbcLAQyt (ORCPT ); Thu, 1 Dec 2016 11:54:49 -0500 Received: from smtprelay0160.hostedemail.com ([216.40.44.160]:47391 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751147AbcLAQys (ORCPT ); Thu, 1 Dec 2016 11:54:48 -0500 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1542:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:2692:2693:2892:3138:3139:3140:3141:3142:3354:3622:3865:3866:3867:3868:3870:3871:3872:3874:4250:4321:5007:6119:6120:6261:6742:7875:7901:7903:10004:10400:10848:10967:11026:11232:11658:11914:12043:12438:12555:12740:12760:12986:13149:13230:13439:14181:14659:14721:21080:21433:21451:30003:30012:30054:30075:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:3,LUA_SUMMARY:none X-HE-Tag: book79_297f67e4cdc50 X-Filterd-Recvd-Size: 3638 Date: Thu, 1 Dec 2016 11:54:43 -0500 From: Steven Rostedt To: Ross Zwisler Cc: linux-kernel@vger.kernel.org, Alexander Viro , Andrew Morton , Christoph Hellwig , Dan Williams , Dave Chinner , Ingo Molnar , Jan Kara , Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@ml01.01.org Subject: Re: [PATCH v3 2/5] dax: add tracepoint infrastructure, PMD tracing Message-ID: <20161201115443.77135c91@gandalf.local.home> In-Reply-To: <1480610271-23699-3-git-send-email-ross.zwisler@linux.intel.com> References: <1480610271-23699-1-git-send-email-ross.zwisler@linux.intel.com> <1480610271-23699-3-git-send-email-ross.zwisler@linux.intel.com> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 1 Dec 2016 09:37:48 -0700 Ross Zwisler wrote: > Tracepoints are the standard way to capture debugging and tracing > information in many parts of the kernel, including the XFS and ext4 > filesystems. Create a tracepoint header for FS DAX and add the first DAX > tracepoints to the PMD fault handler. This allows the tracing for DAX to > be done in the same way as the filesystem tracing so that developers can > look at them together and get a coherent idea of what the system is doing. > > I added both an entry and exit tracepoint because future patches will add > tracepoints to child functions of dax_iomap_pmd_fault() like > dax_pmd_load_hole() and dax_pmd_insert_mapping(). We want those messages to > be wrapped by the parent function tracepoints so the code flow is more > easily understood. Having entry and exit tracepoints for faults also > allows us to easily see what filesystems functions were called during the > fault. These filesystem functions get executed via iomap_begin() and > iomap_end() calls, for example, and will have their own tracepoints. > > For PMD faults we primarily want to understand the type of mapping, the > fault flags, the faulting address and whether it fell back to 4k faults. > If it fell back to 4k faults the tracepoints should let us understand why. > > I named the new tracepoint header file "fs_dax.h" to allow for device DAX > to have its own separate tracing header in the same directory at some > point. > > Here is an example output for these events from a successful PMD fault: > > big-1441 [005] .... 32.582758: xfs_filemap_pmd_fault: dev 259:0 ino > 0x1003 > > big-1441 [005] .... 32.582776: dax_pmd_fault: dev 259:0 ino 0x1003 > shared WRITE|ALLOW_RETRY|KILLABLE|USER address 0x10505000 vm_start > 0x10200000 vm_end 0x10700000 pgoff 0x200 max_pgoff 0x1400 > > big-1441 [005] .... 32.583292: dax_pmd_fault_done: dev 259:0 ino 0x1003 > shared WRITE|ALLOW_RETRY|KILLABLE|USER address 0x10505000 vm_start > 0x10200000 vm_end 0x10700000 pgoff 0x200 max_pgoff 0x1400 NOPAGE > > Signed-off-by: Ross Zwisler > Suggested-by: Dave Chinner > Reviewed-by: Jan Kara Acked-by: Steven Rostedt -- Steve