From patchwork Fri May 8 12:23:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Konstantin Khlebnikov X-Patchwork-Id: 11536415 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8CCFB912 for ; Fri, 8 May 2020 12:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74EA0208D6 for ; Fri, 8 May 2020 12:23:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="kA2ADiyG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726937AbgEHMXT (ORCPT ); Fri, 8 May 2020 08:23:19 -0400 Received: from forwardcorp1p.mail.yandex.net ([77.88.29.217]:34534 "EHLO forwardcorp1p.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726636AbgEHMXS (ORCPT ); Fri, 8 May 2020 08:23:18 -0400 Received: from mxbackcorp1j.mail.yandex.net (mxbackcorp1j.mail.yandex.net [IPv6:2a02:6b8:0:1619::162]) by forwardcorp1p.mail.yandex.net (Yandex) with ESMTP id E6E0A2E153D; Fri, 8 May 2020 15:23:15 +0300 (MSK) Received: from myt4-18a966dbd9be.qloud-c.yandex.net (myt4-18a966dbd9be.qloud-c.yandex.net [2a02:6b8:c00:12ad:0:640:18a9:66db]) by mxbackcorp1j.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id noNF78ywCD-NEWOIxfj; Fri, 08 May 2020 15:23:15 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1588940595; bh=cr1cI1dstvPRsp7XjzJcaiOlA2cPzInYUH9vTttVd4k=; h=In-Reply-To:Message-ID:References:Date:To:From:Subject:Cc; b=kA2ADiyGv3YlEq7Je3o/FUKJKD4JCDDIB8HN+FNhiNMp9ZG180MbJuT2p+YaspCMr vW3pdAs7bqW7Ua+RgFnelbu2NyZwd+NA269zuPSff8Gb9opYnM7x+KREHlRSy3UYHC BnLGZL9ulqOIuhhVIVq+1eO8wctpWFLECfUW9Q6M= Authentication-Results: mxbackcorp1j.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-vpn.dhcp.yndx.net (dynamic-vpn.dhcp.yndx.net [2a02:6b8:b080:7008::1:4]) by myt4-18a966dbd9be.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id sKsCfMvhoh-NEWqunQK; Fri, 08 May 2020 15:23:14 +0300 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client certificate not present) Subject: [PATCH RFC 1/8] dcache: show count of hash buckets in sysctl fs.dentry-state From: Konstantin Khlebnikov To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Alexander Viro Cc: Waiman Long Date: Fri, 08 May 2020 15:23:14 +0300 Message-ID: <158894059427.200862.341530589978120554.stgit@buzz> In-Reply-To: <158893941613.200862.4094521350329937435.stgit@buzz> References: <158893941613.200862.4094521350329937435.stgit@buzz> User-Agent: StGit/0.22-32-g6a05 MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Count of buckets is required for estimating average length of hash chains. Size of hash table depends on memory size and printed once at boot. Let's expose nr_buckets as sixth number in sysctl fs.dentry-state Signed-off-by: Konstantin Khlebnikov --- Documentation/admin-guide/sysctl/fs.rst | 12 ++++++------ fs/dcache.c | 12 ++++++++++-- include/linux/dcache.h | 2 +- 3 files changed, 17 insertions(+), 9 deletions(-) diff --git a/Documentation/admin-guide/sysctl/fs.rst b/Documentation/admin-guide/sysctl/fs.rst index 2a45119e3331..b74df4714ddd 100644 --- a/Documentation/admin-guide/sysctl/fs.rst +++ b/Documentation/admin-guide/sysctl/fs.rst @@ -66,12 +66,12 @@ dentry-state From linux/include/linux/dcache.h:: struct dentry_stat_t dentry_stat { - int nr_dentry; - int nr_unused; - int age_limit; /* age in seconds */ - int want_pages; /* pages requested by system */ - int nr_negative; /* # of unused negative dentries */ - int dummy; /* Reserved for future use */ + long nr_dentry; + long nr_unused; + long age_limit; /* age in seconds */ + long want_pages; /* pages requested by system */ + long nr_negative; /* # of unused negative dentries */ + long nr_buckets; /* count of dcache hash buckets */ }; Dentries are dynamically allocated and deallocated. diff --git a/fs/dcache.c b/fs/dcache.c index b280e07e162b..386f97eaf2ff 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -3139,6 +3139,14 @@ static int __init set_dhash_entries(char *str) } __setup("dhash_entries=", set_dhash_entries); +static void __init dcache_init_hash(void) +{ + dentry_stat.nr_buckets = 1l << d_hash_shift; + + /* shift to use higher bits of 32 bit hash value */ + d_hash_shift = 32 - d_hash_shift; +} + static void __init dcache_init_early(void) { /* If hashes are distributed across NUMA nodes, defer @@ -3157,7 +3165,7 @@ static void __init dcache_init_early(void) NULL, 0, 0); - d_hash_shift = 32 - d_hash_shift; + dcache_init_hash(); } static void __init dcache_init(void) @@ -3185,7 +3193,7 @@ static void __init dcache_init(void) NULL, 0, 0); - d_hash_shift = 32 - d_hash_shift; + dcache_init_hash(); } /* SLAB cache for __getname() consumers */ diff --git a/include/linux/dcache.h b/include/linux/dcache.h index c1488cc84fd9..082b55068e4d 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -65,7 +65,7 @@ struct dentry_stat_t { long age_limit; /* age in seconds */ long want_pages; /* pages requested by system */ long nr_negative; /* # of unused negative dentries */ - long dummy; /* Reserved for future use */ + long nr_buckets; /* count of dcache hash buckets */ }; extern struct dentry_stat_t dentry_stat;