From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3B32C04A68 for ; Thu, 28 Jul 2022 22:30:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229961AbiG1Wab (ORCPT ); Thu, 28 Jul 2022 18:30:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233161AbiG1W3u (ORCPT ); Thu, 28 Jul 2022 18:29:50 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85A3C7B1C1 for ; Thu, 28 Jul 2022 15:29:21 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id s6-20020a170902a50600b0016d2e77252eso1879418plq.18 for ; Thu, 28 Jul 2022 15:29:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc:content-transfer-encoding; bh=HomNzY0vohqpUh0WW0YjSOj5dnamYzXcJXTx/P5QSJY=; b=fugd2W/0FjFmERrZHRJ9Oge/AIsnKYu3XZGvHxf3pm+xuy8aTUBYfcc57eE3YRtOTL P+xx5Ox6IBSsqS8rgGVLo61QqxBSTq4SbiiVEJNr2KG5WgbyNKLsAtVlHA/5yS0M/kQG KzQrjQM+4EYVQ9XV6Xs2zwjFVax8gm0QrGgAonUw3mFiOoNyByq3iKKyWUTHpRGlSP61 Uu3NGhTd+d14uzyYxb7mYrrOxlhlT3f+z0UB3yYuDaoPc4daKB4VR2eeMOophaas8Wks RDWA0dWyFLyXGltBy0qtbnv1I1KlKP5EzUeGIv5jatpDB+3wGwwiWK75H+0lijxbFZKj kiXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc:content-transfer-encoding; bh=HomNzY0vohqpUh0WW0YjSOj5dnamYzXcJXTx/P5QSJY=; b=y3VrJC2QQbir5sPyGHsjOFnV460RgbpbYm6fXBNMZvGaSE4I6wYDfzJpClFsBeIOzp VjQkUx8qQSlHcdQF4yJ+ZOii7v1CeTUQ9pAqPYW0xX4YNBJ1rOW6Wxw5/750vwXmHes+ RyYQnF/YBvKALL1ag0HaUDIXyiOoSTCQjHvahBWBlAN+V1gVL9HYJvqOHz4Aw1Xr6RdL +eQQipIW3kRHVjtnc6rOhisNcZPMXcmVgwwHeD8oBNnnm8rK0TN6WB/VmHgRFWSN6XBC GSX+3DAMDqd2UxMQxe47uT+mWzZc23YVoZ0ncbWOJ58vHTNhO1IiKx7baigwJDEzb48z sNPg== X-Gm-Message-State: ACgBeo1BCWexzBxkE0SW1/+BcAi0uDdhB74Qt6ht32BoIOUwQMwiw3UP d6ytc/q5+RkvIrxozm/+sbPtLpN5hFZi X-Google-Smtp-Source: AA6agR6+1QKKxTjuVaAPBjV66yElg9YxhvqlisXjAfM/4vKw5/WJYArP6PhxtmBbr8Hwlms499G2kXCu/Zzg X-Received: from irogers.svl.corp.google.com ([2620:15c:2d4:203:fd09:96c3:28af:b08f]) (user=irogers job=sendgmr) by 2002:a17:902:6bc5:b0:16c:ea31:5934 with SMTP id m5-20020a1709026bc500b0016cea315934mr903077plt.172.1659047360858; Thu, 28 Jul 2022 15:29:20 -0700 (PDT) Date: Thu, 28 Jul 2022 15:28:35 -0700 In-Reply-To: <20220728222835.3254224-1-irogers@google.com> Message-Id: <20220728222835.3254224-17-irogers@google.com> Mime-Version: 1.0 References: <20220728222835.3254224-1-irogers@google.com> X-Mailer: git-send-email 2.37.1.455.g008518b4e5-goog Subject: [PATCH v2 16/16] perf jevents: Fold strings optimization From: Ian Rogers To: John Garry , Will Deacon , James Clark , Mike Leach , Leo Yan , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Andi Kleen , Zhengjun Xing , Ravi Bangoria , Kan Liang , Adrian Hunter , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org Cc: Stephane Eranian , Ian Rogers Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a shorter string ends a longer string then the shorter string may reuse the longer string at an offset. For example, on x86 the event arith.cycles_div_busy and cycles_div_busy can be folded, even though they have difference names the strings are identical after 6 characters. cycles_div_busy can reuse the arith.cycles_div_busy string at an offset of 6. In pmu-events.c this looks like the following where the 'also:' lists folded strings: /* offset=3D177541 */ "arith.cycles_div_busy\000\000pipeline\000Cycles the = divider is busy\000\000\000event=3D0x14,period=3D2000000,umask=3D0x1\000\00= 0\000\000\000\000\000\000\000" /* also: cycles_div_busy\000\000pipeline\000= Cycles the divider is busy\000\000\000event=3D0x14,period=3D2000000,umask= =3D0x1\000\000\000\000\000\000\000\000\000 */ As jevents.py combines multiple strings for an event into a larger string, the amount of folding is minimal as all parts of the event must align. Other organizations can benefit more from folding, but lose space by say recording more offsets. Signed-off-by: Ian Rogers --- tools/perf/pmu-events/jevents.py | 55 ++++++++++++++++++++++++++++---- 1 file changed, 48 insertions(+), 7 deletions(-) diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jeven= ts.py index f6f0459a261d..e446b8d9a3b2 100755 --- a/tools/perf/pmu-events/jevents.py +++ b/tools/perf/pmu-events/jevents.py @@ -80,7 +80,9 @@ class BigCString: are all the other C strings (to avoid memory issues the string itself is held as a list of strings). The offsets within the big string are recorded and when stored to disk these don't need - relocation. + relocation. To reduce the size of the string further, identical + strings are merged. If a longer string ends-with the same value as a + shorter string, these entries are also merged. """ strings: Set[str] big_string: Sequence[str] @@ -96,6 +98,33 @@ class BigCString: def compute(self) -> None: """Called once all strings are added to compute the string and offsets= .""" =20 + folded_strings =3D {} + # Determine if two strings can be folded, ie. let 1 string use the + # end of another. First reverse all strings and sort them. + sorted_reversed_strings =3D sorted([x[::-1] for x in self.strings]) + + # Strings 'xyz' and 'yz' will now be [ 'zy', 'zyx' ]. Scan forward + # for each string to see if there is a better candidate to fold it + # into, in the example rather than using 'yz' we can use'xyz' at + # an offset of 1. We record which string can be folded into which + # in folded_strings, we don't need to record the offset as it is + # trivially computed from the string lengths. + for pos,s in enumerate(sorted_reversed_strings): + best_pos =3D pos + for check_pos in range(pos + 1, len(sorted_reversed_strings)): + if sorted_reversed_strings[check_pos].startswith(s): + best_pos =3D check_pos + else: + break + if pos !=3D best_pos: + folded_strings[s[::-1]] =3D sorted_reversed_strings[best_pos][::-1= ] + + # Compute reverse mappings for debugging. + fold_into_strings =3D collections.defaultdict(set) + for key, val in folded_strings.items(): + if key !=3D val: + fold_into_strings[val].add(key) + # big_string_offset is the current location within the C string # being appended to - comments, etc. don't count. big_string is # the string contents represented as a list. Strings are immutable @@ -104,13 +133,25 @@ class BigCString: big_string_offset =3D 0 self.big_string =3D [] self.offsets =3D {} - # Emit all strings in a sorted manner. + + # Emit all strings that aren't folded in a sorted manner. for s in sorted(self.strings): - self.offsets[s] =3D big_string_offset - self.big_string.append(f'/* offset=3D{big_string_offset} */ "') - self.big_string.append(s) - self.big_string.append('"\n') - big_string_offset +=3D c_len(s) + if s not in folded_strings: + self.offsets[s] =3D big_string_offset + self.big_string.append(f'/* offset=3D{big_string_offset} */ "') + self.big_string.append(s) + self.big_string.append('"') + if s in fold_into_strings: + self.big_string.append(' /* also: ' + ', '.join(fold_into_string= s[s]) + ' */') + self.big_string.append('\n') + big_string_offset +=3D c_len(s) + continue + + # Compute the offsets of the folded strings. + for s in folded_strings.keys(): + assert s not in self.offsets + folded_s =3D folded_strings[s] + self.offsets[s] =3D self.offsets[folded_s] + c_len(folded_s) - c_len= (s) =20 _bcs =3D BigCString() =20 --=20 2.37.1.455.g008518b4e5-goog