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 X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AB50EC433E0 for ; Wed, 10 Feb 2021 00:30:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 70A1664E4F for ; Wed, 10 Feb 2021 00:30:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233905AbhBJA3v (ORCPT ); Tue, 9 Feb 2021 19:29:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234205AbhBIU47 (ORCPT ); Tue, 9 Feb 2021 15:56:59 -0500 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3026C061794 for ; Tue, 9 Feb 2021 11:03:20 -0800 (PST) Received: by mail-pj1-x1029.google.com with SMTP id d2so2227351pjs.4 for ; Tue, 09 Feb 2021 11:03:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=delphix.com; s=google; h=from:to:cc:subject:date:message-id; bh=3O/mqypFsO3O218VUQ7AaVDZ9919y4ACFmjTnjCZTqU=; b=dMOEzna3+iazmZ7hOhH5wTI57l3vPWBgjjhR0ERX4wB2uI9yQwzXvvpwDSyNrk4kAS Ike6XHQPYvTVdFZqE2hghkphFy1KuTuuL8HYTGNwPGCwtq46I4efHQ45krOKYKhEVo2U Nl6v0Qfa6QJYBrAe4J7yvW04ZwVsrizxNOWR4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=3O/mqypFsO3O218VUQ7AaVDZ9919y4ACFmjTnjCZTqU=; b=liWggmpdVloXROcYD6EEOrDfnCYuuEQ5W0HZL0a4ZLaKFhCrjeQUrct6DMQvj6NcGL gjWA6DVxsLCIrJ8i6oAI5C+rs4VNgP5oWx+M4qivPBJZhjebAhDLvsBgSIJ7PsommJL2 me0S9MBTOx2Syb2oLj1r7KJ9wR38uzlkTK8D4Xfu+QmCinfp5DVauay1yFCHUJ2lE83p JhxEx19MqtV9yUuJ0+ylHz8NiFblfbv2D3yy5G4qyh13qdQ/m4LBCTG2yHbmEiP7H9ZD CLfpjHiZByi/RIPPO/jpyaP4M9mHNJBSqfOhCGTuVz4fObmbkp1AbPI7E4yzi1bfvqF8 EuAg== X-Gm-Message-State: AOAM531BKJpMbCWmgccMXVNSdRKKVAUFzVuWthTcPS9UIdn2cyvC06XA qzKO/J7EYnyDLw1PlptWC+WtNg== X-Google-Smtp-Source: ABdhPJyfvEp5pATS1gcO5Hh3siii2AtaO2ih6dLkADvoH4jvuRkVkIv4v+Ll+vt/8Rk0YVkUBGGZfg== X-Received: by 2002:a17:902:c284:b029:e1:8863:b3d6 with SMTP id i4-20020a170902c284b02900e18863b3d6mr22312104pld.64.1612897400252; Tue, 09 Feb 2021 11:03:20 -0800 (PST) Received: from sd-kernel.dcol2.delphix.com (DELPHIX-COR.ear1.SanJose1.Level3.net. [4.15.123.66]) by smtp.googlemail.com with ESMTPSA id 123sm23324903pfd.91.2021.02.09.11.03.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Feb 2021 11:03:19 -0800 (PST) From: Serapheim Dimitropoulos X-Google-Original-From: Serapheim Dimitropoulos To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, osandov@osandov.com, urezki@gmail.com, serapheim@delphix.com Subject: [PATCH v2] mm/vmalloc: use rb_tree instead of list for vread() lookups Date: Tue, 9 Feb 2021 19:02:53 +0000 Message-Id: <20210209190253.108763-1-serapheim@delphix.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org vread() has been linearly searching vmap_area_list for looking up vmalloc areas to read from. These same areas are also tracked by a rb_tree (vmap_area_root) which offers logarithmic lookup. This patch modifies vread() to use the rb_tree structure instead of the list and the speedup for heavy /proc/kcore readers can be pretty significant. Below are the wall clock measurements of a Python application that leverages the drgn debugging library to read and interpret data read from /proc/kcore. Before the patch: ----- $ time sudo sdb -e 'dbuf | head 3000 | wc' (unsigned long)3000 real 0m22.446s user 0m2.321s sys 0m20.690s ----- With the patch: ----- $ time sudo sdb -e 'dbuf | head 3000 | wc' (unsigned long)3000 real 0m2.104s user 0m2.043s sys 0m0.921s ----- Signed-off-by: Serapheim Dimitropoulos --- Changed in v2: - Use __find_vmap_area() for initial lookup but keep iteration via va->list. mm/vmalloc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 49ab9b6c001d..eb133d000394 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2860,7 +2860,10 @@ long vread(char *buf, char *addr, unsigned long count) count = -(unsigned long) addr; spin_lock(&vmap_area_lock); - list_for_each_entry(va, &vmap_area_list, list) { + va = __find_vmap_area((unsigned long)addr); + if (!va) + goto finished; + list_for_each_entry_from(va, &vmap_area_list, list) { if (!count) break; -- 2.17.1