From owner-freebsd-hackers@freebsd.org  Mon Nov 21 20:23:32 2016
Return-Path: <owner-freebsd-hackers@freebsd.org>
Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 6528AC4D86E
 for <freebsd-hackers@mailman.ysv.freebsd.org>;
 Mon, 21 Nov 2016 20:23:32 +0000 (UTC)
 (envelope-from Volker.Lendecke@SerNet.DE)
Received: from mail.SerNet.de (mail1.SerNet.de [193.175.80.2])
 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 2E261D38
 for <freebsd-hackers@freebsd.org>; Mon, 21 Nov 2016 20:23:31 +0000 (UTC)
 (envelope-from Volker.Lendecke@SerNet.DE)
Received: from intern.SerNet.DE by mail.SerNet.DE with esmtps (Exim 4.84_2 #1)
 id 1c8v7g-0004oD-Ed; Mon, 21 Nov 2016 21:23:28 +0100
Received: by intern.sernet.de
 id 1c8v7g-0000d0-CH; Mon, 21 Nov 2016 21:23:28 +0100
Date: Mon, 21 Nov 2016 21:23:25 +0100
From: Volker Lendecke <Volker.Lendecke@SerNet.DE>
To: Konstantin Belousov <kostikbel@gmail.com>
Cc: freebsd-hackers@freebsd.org
Subject: Re: process shared mutexes?
Message-ID: <20161121202325.GA32463@sernet.de>
Reply-To: Volker.Lendecke@SerNet.DE
References: <20161121133528.GA30947@sernet.de>
 <20161121135036.GY54029@kib.kiev.ua>
 <20161121141616.GB30947@sernet.de>
 <20161121151040.GA54029@kib.kiev.ua>
 <20161121152542.GA31733@sernet.de>
 <20161121155823.GB54029@kib.kiev.ua>
 <20161121161454.GA32128@sernet.de>
 <20161121164109.GC54029@kib.kiev.ua>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20161121164109.GC54029@kib.kiev.ua>
User-Agent: Mutt/1.5.23 (2014-03-12)
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers/>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 21 Nov 2016 20:23:32 -0000

On Mon, Nov 21, 2016 at 06:41:09PM +0200, Konstantin Belousov wrote:
> > So -- all of the above discussion becomes irrelevant if I change tdb
> > such that it keeps the mutex area mmappe'd at least once? Then no GC
> > will kick in regardless of the sysctl? This would be possible, because
> > we use mutexes on so-called CLEAR_IF_FIRST databases only. When the last
> > process closes the db, it will be wiped on the next open.
> 
> If the file is mmaped, then yes, the mutex must be not destroyed.  If it
> is, then there is a bug in the current implementation.

Just wanted to say thanks! With a pretty simple change to tdb our
tdbtorture runs smoothly on FreeBSD 11!

Volker