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 B053DC433E9 for ; Mon, 8 Feb 2021 18:27:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6F36A64E84 for ; Mon, 8 Feb 2021 18:27:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235644AbhBHS1p (ORCPT ); Mon, 8 Feb 2021 13:27:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234134AbhBHPx5 (ORCPT ); Mon, 8 Feb 2021 10:53:57 -0500 Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A61A7C061786 for ; Mon, 8 Feb 2021 07:53:17 -0800 (PST) Received: by mail-pg1-x531.google.com with SMTP id e7so1536119pge.0 for ; Mon, 08 Feb 2021 07:53:17 -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=bv31c/MDD+J9/ofoLSaaCjpSKbdjhNAUexmwFwimhPM=; b=fWcAPommuKM/IFRTzUIO/AweTrcvpcC2yZfhuldGppsRcp5aDoCIShY0yNhUTDVBC/ 3q0DLLYxPHjNpIEc+1KAo0tgx+RSvA+ogLIcd2ie3Pw8l1GIWqamVnBdT1b9K7mqvls3 m07o5G88evuPMnIQo8CowWg5mtQITzXrpMHIY= 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=bv31c/MDD+J9/ofoLSaaCjpSKbdjhNAUexmwFwimhPM=; b=rE0qlkncHb6id5eq5gFAp1GWTSUcbtI9IyOAXghrW+/LokRDC9LEfTuWdMiQcPtb5h e6bf/KRtv8Rq5ShedEJ3Hzmsw5wsHK/DbJ6UlAjILkEHxwpNKkGj2AItFJY9/eWIoQTn 9jnyegbB5Nl5faTQalNMvq0qxSCvNdwmO3tcYDNIA6t8c2VerqlociQAeLlwJZmOQJ2g vhAI1ag2cyggTSW5F2zULfJlR+a0W9+NlRJSArwI2KRtD8v+yHd4frSKehP4/a2f6nd/ hSCj89LL9u+Ck1r85EssVFJ15WLdl41eFOcAziyRA+JbneX9TPS0zJXJXqxPwGWjzMXJ ZU+g== X-Gm-Message-State: AOAM531/nktLmhAdp0DpwhkNw/3hyegWe03e6MhVuRCZ3+j4Gpt7yoKQ Lf/VQvDLwTsxyxN314J2W5Dk+g== X-Google-Smtp-Source: ABdhPJzZVqXn4S2LaV+CAbkdMLUFRYLPB7Lbycu+tTQD4ybzSfOoN7KknTaeBTt2lt/2D6cZj9UJKw== X-Received: by 2002:aa7:98d2:0:b029:1da:3374:4777 with SMTP id e18-20020aa798d20000b02901da33744777mr11031393pfm.45.1612799597208; Mon, 08 Feb 2021 07:53:17 -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 cm7sm5048427pjb.43.2021.02.08.07.53.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Feb 2021 07:53:16 -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, serapheim@delphix.com Subject: [PATCH] mm/vmalloc: use rb_tree instead of list for vread() lookups Date: Mon, 8 Feb 2021 15:53:03 +0000 Message-Id: <20210208155303.10523-1-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 2500 | wc' (unsigned long)2500 real 0m21.128s user 0m2.321s sys 0m19.227s ----- With the patch: ----- $ time sudo sdb -e 'dbuf | head 2500 | wc' (unsigned long)2500 real 0m1.870s user 0m1.628s sys 0m0.660s ----- Signed-off-by: Serapheim Dimitropoulos --- mm/vmalloc.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 49ab9b6c001d..86343b879938 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2851,6 +2851,7 @@ long vread(char *buf, char *addr, unsigned long count) { struct vmap_area *va; struct vm_struct *vm; + struct rb_node *node; char *vaddr, *buf_start = buf; unsigned long buflen = count; unsigned long n; @@ -2860,17 +2861,15 @@ 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) { - if (!count) - break; - + va = __find_vmap_area((unsigned long)addr); + if (!va) + goto finished; + while (count) { if (!va->vm) - continue; + goto next_node; vm = va->vm; vaddr = (char *) vm->addr; - if (addr >= vaddr + get_vm_area_size(vm)) - continue; while (addr < vaddr) { if (count == 0) goto finished; @@ -2889,6 +2888,12 @@ long vread(char *buf, char *addr, unsigned long count) buf += n; addr += n; count -= n; + +next_node: + node = rb_next(&va->rb_node); + if (!node) + break; + va = rb_entry(node, struct vmap_area, rb_node); } finished: spin_unlock(&vmap_area_lock); -- 2.17.1