Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com
Date:	Mon, 24 Oct 2005 15:40:40 +0200
From:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: Scalability problem with Pthread Read/Write Locks
Message-ID:	<20051024134040.GD24278@calimero.vinschen.de>
Reply-To:	cygwin AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
References:	<20051023124539 DOT 21428 DOT qmail AT web32008 DOT mail DOT mud DOT yahoo DOT com>
Mime-Version:	1.0
In-Reply-To:	<20051023124539.21428.qmail@web32008.mail.mud.yahoo.com>
User-Agent:	Mutt/1.4.2i

On Oct 23 05:45, Johan De Taeye wrote:
> 
> My multi-threaded application is creating a lot of
> pthread_rwlock objects to protect access to my objects.
> I am noticing that this doesn't scale up well. As the number
> of active objects being created/changed/deleted increases
> into the thousands, the runtime performance degrades very
> badly.
> 
> When investigating the problem I noticed from the source code
> in the files winsup/cygwin/thread.h and
> winsup/cygwin/thread.cc that a static double-linked list
> (called rwlocks) is used to keep track of all rwlocks present
> in the process. Removal of an element in the list is O(n) and
> explains the behavior of my application.
> 
> When compiling under Linux no such scalability problems are
> found. (I believe the pthreads implementation there doesn't
> need to  keep track of the active rwlocks)
> 
> Finally the question: Could/should the =list= data structure
> be replaced with a =set= to provide better scalability?

Maybe, but http://cygwin.com/acronyms/#SHTDI.  A patch which optimizes
cases like this are always thoughtfully considered.  If you're willing
to help, have a look on http://cygwin.com/contrib.html.  However, I'd
think we shouldn't change this for the upcoming 1.5.19 release which
already contains a lot more changes than we had in mind once.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat, Inc.

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/

- Raw text -