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=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 C5485C33CAD for ; Mon, 13 Jan 2020 14:55:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 954D0207FF for ; Mon, 13 Jan 2020 14:55:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hCzwWIuh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728928AbgAMOzu (ORCPT ); Mon, 13 Jan 2020 09:55:50 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:51250 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726567AbgAMOzt (ORCPT ); Mon, 13 Jan 2020 09:55:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=zh4QUZLzvgMWwTWktPzWJ7VG+SXjfjlk+HJG7tNPPF8=; b=hCzwWIuhWrKQ4ZB+odRihAPPp 9/2+9RV0pnAD53kgq7fzWS1an+ByKVlBpMgU8aTShWp8bZqPD+uUehIrUjRj8AbY/1vI6YeHobzu2 /aY/19P4ierCov3QHXXN0Z+XCmsgjgqpr4XjbNQa0mp5byT68X+ngK9MJffVxu70VnUz5XRTJFOC4 n9XoVPle85NWAvs2mHQqkP62ms1D9jWgsikoeFwtP8QGVdMOxYf65hFpv0A3tS/y83L8ePChsMLaP BTKP97b9aXRHpRdq7gVn2UYh+nz4AJtBsVGuMhkpffktLE2gCk/LNxpnGjXGYyUWOWcn8Qv3Y0NXB 2Gjkg9kTA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1ir185-0002Uk-JG; Mon, 13 Jan 2020 14:55:45 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 76EDA304121; Mon, 13 Jan 2020 15:54:07 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id BB930201D941B; Mon, 13 Jan 2020 15:55:42 +0100 (CET) Date: Mon, 13 Jan 2020 15:55:42 +0100 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , linux-kernel@vger.kernel.org, Bart Van Assche Subject: Re: [PATCH v2 1/6] locking/lockdep: Track number of zapped classes Message-ID: <20200113145542.GV2844@hirez.programming.kicks-ass.net> References: <20191216151517.7060-1-longman@redhat.com> <20191216151517.7060-2-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191216151517.7060-2-longman@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 16, 2019 at 10:15:12AM -0500, Waiman Long wrote: > The whole point of the lockdep dynamic key patch is to allow unused > locks to be removed from the lockdep data buffers so that existing > buffer space can be reused. However, there is no way to find out how > many unused locks are zapped and so we don't know if the zapping process > is working properly. > > Add a new nr_zapped_classes variable to track that and show it in > /proc/lockdep_stats if it is non-zero. > > diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c > index dadb7b7fba37..d98d349bb648 100644 > --- a/kernel/locking/lockdep_proc.c > +++ b/kernel/locking/lockdep_proc.c > @@ -336,6 +336,15 @@ static int lockdep_stats_show(struct seq_file *m, void *v) > seq_printf(m, " debug_locks: %11u\n", > debug_locks); > > + /* > + * Zappped classes and lockdep data buffers reuse statistics. > + */ > + if (!nr_zapped_classes) > + return 0; > + > + seq_puts(m, "\n"); > + seq_printf(m, " zapped classes: %11lu\n", > + nr_zapped_classes); > return 0; > } Why is that conditional?