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=-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 C3B2AC433ED for ; Fri, 30 Apr 2021 05:58:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A33BB61459 for ; Fri, 30 Apr 2021 05:58:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230315AbhD3F6z (ORCPT ); Fri, 30 Apr 2021 01:58:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:52090 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230215AbhD3F6z (ORCPT ); Fri, 30 Apr 2021 01:58:55 -0400 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 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org 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; _