From patchwork Fri Apr 30 05:58:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12232473 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=-15.7 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 autolearn=ham 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 E5CD3C433B4 for ; Fri, 30 Apr 2021 05:58:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 99434613A9 for ; Fri, 30 Apr 2021 05:58:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 99434613A9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3B16A8E000E; Fri, 30 Apr 2021 01:58:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 361698D000B; Fri, 30 Apr 2021 01:58:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 24FC88E000E; Fri, 30 Apr 2021 01:58:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0252.hostedemail.com [216.40.44.252]) by kanga.kvack.org (Postfix) with ESMTP id 08E658D000B for ; Fri, 30 Apr 2021 01:58:09 -0400 (EDT) Received: from smtpin39.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id C13E28249980 for ; Fri, 30 Apr 2021 05:58:08 +0000 (UTC) X-FDA: 78087977856.39.ECAA558 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf21.hostedemail.com (Postfix) with ESMTP id C7D24E000119 for ; Fri, 30 Apr 2021 05:58:04 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 76442613A9; Fri, 30 Apr 2021 05:58:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1619762287; bh=JwKzgefXGZe8GsV5ZAknzYlHM2ZfBG6l+9LSBwPE7s0=; h=Date:From:To:Subject:In-Reply-To:From; b=kmuEqa1rLZw4iJJgW4QBEkVAtiWeDVEF+67oLfX+TBo3AiB7HkQvV3/cQycY7pIId LcG3OInVYgIhhfNEMi5+MZzmBk9LPIWBwvyaD14oHcpIUpvmHf06o4Y9fwBvke8BQv WjmHHPsXr+gRI2Av1qvNcjVOt39dNVyWzBAkGQR8= Date: Thu, 29 Apr 2021 22:58:07 -0700 From: Andrew Morton To: akpm@linux-foundation.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, serapheim.dimitro@delphix.com, serapheim@delphix.com, torvalds@linux-foundation.org, urezki@gmail.com Subject: [patch 096/178] mm/vmalloc: use rb_tree instead of list for vread() lookups Message-ID: <20210430055807.76OL5vx7b%akpm@linux-foundation.org> In-Reply-To: <20210429225251.02b6386d21b69255b4f6c163@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C7D24E000119 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=kmuEqa1r; dmarc=none; spf=pass (imf21.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Stat-Signature: 1oxorbsupbwn4kazi1769m4rmmyt9f7u Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf21; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619762284-271917 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Serapheim Dimitropoulos Subject: mm/vmalloc: use rb_tree instead of list for vread() lookups 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 ----- Link: https://lkml.kernel.org/r/20210209190253.108763-1-serapheim@delphix.com Signed-off-by: Serapheim Dimitropoulos Reviewed-by: Uladzislau Rezki (Sony) Signed-off-by: Andrew Morton --- mm/vmalloc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/vmalloc.c~mm-vmalloc-use-rb_tree-instead-of-list-for-vread-lookups +++ a/mm/vmalloc.c @@ -2894,7 +2894,10 @@ long vread(char *buf, char *addr, unsign 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;