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Thu, 11 Dec 2025 23:35:27 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id lWUSMD9VO2mQJwAAD6G6ig (envelope-from ); Thu, 11 Dec 2025 23:35:27 +0000 Date: Thu, 11 Dec 2025 15:35:23 -0800 From: Tony Jones To: James Clark Cc: Ian Rogers , Namhyung Kim , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Howard Chu , Stephen Brennan , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH v1] perf addr2line: Add a libdw implementation Message-ID: References: <20251122093934.94971-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Flag: NO X-Spam-Score: -4.30 X-Spam-Level: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; MISSING_XM_UA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[13]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[google.com,kernel.org,infradead.org,redhat.com,linux.intel.com,intel.com,gmail.com,oracle.com,vger.kernel.org]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; URIBL_BLOCKED(0.00)[imap1.dmz-prg2.suse.org:helo]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid] On Thu, Nov 27, 2025 at 12:16:29PM +0000, James Clark wrote: > If the llvm addr2line implementation is also supposed to be slow, it just > means we're trading speed with accuracy with this change. Hard to say what > the default should be in that case. I originally inquired about this (and was going to code up a patch using libdw but Ian beat me to it) as we had a customer bug complaining about the performance of the binutils (/usr/bin/addr2line) forking solution and llvm isn't presently an option for us. Using the forked addr2line the customer data set takes real: 54m15.023s user: 40m57.719s sys: 11m22.461s for perf script -F ip,srcline (with numerous time-out errors). Versus real: 6m6.598s user: 5m32.603s sys: 0m1.768s with this proposed libdw patch. I'm also unfortunately seeing similar wrong file/line# issues. This said I think given that libdw is being used anyways and how poor the /usr/bin/addr2line performance is that it's worth digging deeper into what the issues are with libdw. I'll try to look at it some more next week. Thanks for the patch Ian! Tony --------- Tony Jones SUSE Kernel Performance Team