From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Newsgroups: gmane.emacs.bugs Subject: bug#65491: [PATCH] Improve performance allocating vectors Date: Mon, 25 Sep 2023 18:06:37 +0200 Message-ID: <40613B9F-8EAA-42A9-9D42-929644A5A2C2@gmail.com> References: <6B2EDD07-AAEB-40E8-B369-F634296BD3D9@gmail.com> Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.15\)) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="19991"; mail-complaints-to="usenet@ciao.gmane.io" Cc: 65491@debbugs.gnu.org, Eli Zaretskii To: Stefan Monnier Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Mon Sep 25 18:08:22 2023 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1qko8D-0004zb-VU for geb-bug-gnu-emacs@m.gmane-mx.org; Mon, 25 Sep 2023 18:08:21 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qko7o-0007z6-5n; Mon, 25 Sep 2023 12:07:56 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qko7j-0007xJ-Ob for bug-gnu-emacs@gnu.org; Mon, 25 Sep 2023 12:07:52 -0400 Original-Received: from debbugs.gnu.org ([2001:470:142:5::43]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qko7i-0007gF-AO for bug-gnu-emacs@gnu.org; Mon, 25 Sep 2023 12:07:51 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1qko7u-0000GA-Et for bug-gnu-emacs@gnu.org; Mon, 25 Sep 2023 12:08:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Mon, 25 Sep 2023 16:08:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 65491 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: patch Original-Received: via spool by 65491-submit@debbugs.gnu.org id=B65491.1695658022914 (code B ref 65491); Mon, 25 Sep 2023 16:08:02 +0000 Original-Received: (at 65491) by debbugs.gnu.org; 25 Sep 2023 16:07:02 +0000 Original-Received: from localhost ([127.0.0.1]:46481 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1qko6w-0000Eg-EM for submit@debbugs.gnu.org; Mon, 25 Sep 2023 12:07:02 -0400 Original-Received: from mail-lj1-x229.google.com ([2a00:1450:4864:20::229]:46571) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1qko6s-0000E0-Gm for 65491@debbugs.gnu.org; Mon, 25 Sep 2023 12:07:01 -0400 Original-Received: by mail-lj1-x229.google.com with SMTP id 38308e7fff4ca-2c02e232c48so114614361fa.1 for <65491@debbugs.gnu.org>; Mon, 25 Sep 2023 09:06:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1695658000; x=1696262800; darn=debbugs.gnu.org; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:sender:from:to:cc:subject :date:message-id:reply-to; bh=Mt1jSXP4RPmpfrohS02UtPq6AeSrsb1WdaJdR/n1ZQg=; b=Lw0XYJyJsGev9o7LGAkLvstTfsreX00nybjh0TA8TWsYofOkQGZ8WLIpnRmY58evW8 cAneh4VIM/Lbc3QSbW0PZmRbQV/RbXSCvII7irVt6PlRBCw5mEmozarcoFHv5+ZV3f2H KzyujC+5NDqUuP+2Us6XHAbSC/Io1IDmwRPhusI7YUAnRJQNupQQ5z8zD7d/KS1VgZXV xz3WoRYAA14fU5tnZ339Nbl2QPy6CsdLnCi5kTn3SbzeRIJIYLUurhWX/NzbeUkvbEpt QyLXAHKslpcapkfX33gc6Dpc1ggeII6IfUL6/mjtYY/rhdGAJsC53QTmzxEzajXk3+4Y rSWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695658000; x=1696262800; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:sender:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=Mt1jSXP4RPmpfrohS02UtPq6AeSrsb1WdaJdR/n1ZQg=; b=if/nWsufeMfziN1wuqQ4JBP6g9mpfD5RyzLBnbbFMpXOB0RldijyxoVGANPx7Z0sW6 +wV+4xgEzi1Hx31h1/e1j2gDjTHkrgfaYpWWvta6CSp6xYZUp9NYK+RimtplagawPx56 XV7s0/ItW0oQfOxhBKSPTivLZ1j47JitGiR/9zu9lArFJeqErAjsNgEd9SsbmE2GuILK yrSx/odpKtsTgAOj/PPpB7AtAohtB3bBqxKe4tzdfqqMGonvCe6UcM0p3UaCPsW9WAeF JWbQ/hezFseYR0Gzd76rE+FaVXwKIBhEZDpgNGnfVN50fu8JTVMH6AMAaoT3PzuB5EQ/ vS3A== X-Gm-Message-State: AOJu0YzQCaiF0Rf4CDmP0F7+iDkARYrJ8zSRaTwzb+lTYfKZdLUhdUwY l1gMzs1CzTTjJI70YvE6DCw= X-Google-Smtp-Source: AGHT+IFkXRMJTTrkX59BZod+R3NvVjcuGonWctXAicg6zhPeqxf0CHBmkeiMBfkVnMNUqw1wdIXrRA== X-Received: by 2002:a2e:3c03:0:b0:2c0:1a80:dfb with SMTP id j3-20020a2e3c03000000b002c01a800dfbmr5416797lja.27.1695657998806; Mon, 25 Sep 2023 09:06:38 -0700 (PDT) Original-Received: from smtpclient.apple (c188-150-165-235.bredband.tele2.se. [188.150.165.235]) by smtp.gmail.com with ESMTPSA id e1-20020a2e8ec1000000b002b9bf5b071bsm2269077ljl.20.2023.09.25.09.06.38 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 Sep 2023 09:06:38 -0700 (PDT) In-Reply-To: <6B2EDD07-AAEB-40E8-B369-F634296BD3D9@gmail.com> X-Mailer: Apple Mail (2.3654.120.0.1.15) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.bugs:271341 Archived-At: > - Reducing the `vector_free_lists` array to its actually used first = half does improve performance a bit, even with subsequent scanning = speed-ups. > - The previously mentioned hack where scanning begins in the most = recently added bucket is surprisingly effective, often even more so than = a bitmap, but I'm wary of it being brittle. Need more measurements. These two changes were simple, fairly effective, and found to be = reasonably safe (in the sense that they are unlikely to make performance = worse), so I pushed them to master. This way we should be better off = even if no further progress is made. As mentioned, a bitmap is essentially as good as or better than the = last-used-index heuristic but I went with the latter because it involved = a lot less code. This can be changed. But it is possible to do better: size-homogeneous blocks, where each = block only houses vectors of a single size, have the major benefit that = live_small_vector_holding no longer needs to traverse half the block on = average but becomes is done in constant time. Sweeping, always = performance-critical since it traverses both living and dead objects, = becomes slightly faster. There is also no free-list array scanning at = all. Benchmarks suggest that larger homogeneous blocks (32 KiB, say) would be = beneficial, but we need to look at the potential extra fragmentation = caused by allocating a big block for each odd vector size.