From patchwork Wed Aug 30 08:47:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 9928955 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 59C396022E for ; Wed, 30 Aug 2017 08:48:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4468A28174 for ; Wed, 30 Aug 2017 08:48:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 38DB528179; Wed, 30 Aug 2017 08:48:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ECC7128174 for ; Wed, 30 Aug 2017 08:48:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751316AbdH3Iry (ORCPT ); Wed, 30 Aug 2017 04:47:54 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:39328 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271AbdH3Irx (ORCPT ); Wed, 30 Aug 2017 04:47:53 -0400 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=0E6Xlo9VNPCvxeQM8/FJ+u3E4p6XA2PhHAE9gnZndv8=; b=Br8Yh5KeuyNJgDqCygQkyTfhM tMU6ax7tIjiCxBO6beN6f9Tyh0iuKsEG1tY3woRCEADhSvTNCp0vQ+lbPlDGRKIRzbH7S6PrYsxHo aED2h2E+ZJCf21oTzd9GLDuvS4QcEY3k34po4TmbSTGEGUiQAOm+znRXY5iemiPB9ocXWYdB4mY+c 2utNJ2A4drOavK4HijCyuVlBx9Pf18h6N7sNqQnmbT5meHwt3T7H8eTh+lvStW6zr5U8palfSmG/j +QBfYD+v4QHTYmeEUOcpLddgbvNnjxdOWPk0Hkcn4o1214sHx3SiyXCFKowp//xeLNHh2UbUitLHV Lbr0YRQZg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop) by bombadil.infradead.org with esmtpsa (Exim 4.87 #1 (Red Hat Linux)) id 1dmyf6-00018X-Ne; Wed, 30 Aug 2017 08:47:48 +0000 Received: by worktop (Postfix, from userid 1000) id 1E72D6E06BA; Wed, 30 Aug 2017 10:47:46 +0200 (CEST) Date: Wed, 30 Aug 2017 10:47:46 +0200 From: Peter Zijlstra To: Sergey Senozhatsky Cc: Byungchul Park , Bart Van Assche , "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "martin.petersen@oracle.com" , "axboe@kernel.dk" , "linux-scsi@vger.kernel.org" , "sfr@canb.auug.org.au" , "linux-next@vger.kernel.org" , kernel-team@lge.com Subject: Re: possible circular locking dependency detected [was: linux-next: Tree for Aug 22] Message-ID: <20170830084746.GC660@worktop.programming.kicks-ass.net> References: <20170822183816.7925e0f8@canb.auug.org.au> <20170822104708.GA491@jagdpanzerIV.localdomain> <1503438234.2508.27.camel@wdc.com> <20170823000304.GK20323@X58A-UD3R> <20170830052037.GA432@jagdpanzerIV.localdomain> <20170830054334.GF3240@X58A-UD3R> <20170830061511.GA330@jagdpanzerIV.localdomain> <20170830084207.GL32112@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20170830084207.GL32112@worktop.programming.kicks-ass.net> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Wed, Aug 30, 2017 at 10:42:07AM +0200, Peter Zijlstra wrote: > > So the overhead looks to be spread out over all sorts, which makes it > harder to find and fix. > > stack unwinding is done lots and is fairly expensive, I've not yet > checked if crossrelease does too much of that. Aah, we do an unconditional stack unwind for every __lock_acquire() now. It keeps a trace in the xhlocks[]. Does the below cure most of that overhead? diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 44c8d0d17170..7b872036b72e 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -4872,7 +4872,7 @@ static void add_xhlock(struct held_lock *hlock) xhlock->trace.max_entries = MAX_XHLOCK_TRACE_ENTRIES; xhlock->trace.entries = xhlock->trace_entries; xhlock->trace.skip = 3; - save_stack_trace(&xhlock->trace); + /* save_stack_trace(&xhlock->trace); */ } static inline int same_context_xhlock(struct hist_lock *xhlock)