From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1756003AbaD1NfB (ORCPT <rfc822;w@1wt.eu>);
	Mon, 28 Apr 2014 09:35:01 -0400
Received: from mx1.redhat.com ([209.132.183.28]:34906 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752160AbaD1NfA (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 28 Apr 2014 09:35:00 -0400
Date: Mon, 28 Apr 2014 15:34:43 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: linux-kernel@vger.kernel.org, Corey Ashford <cjashfor@linux.vnet.ibm.com>,
        David Ahern <dsahern@gmail.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Ingo Molnar <mingo@kernel.org>, Paul Mackerras <paulus@samba.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jean Pihet <jean.pihet@linaro.org>
Subject: Re: [PATCH 2/3] perf tools: Cache dso data file descriptor
Message-ID: <20140428133443.GE18628@krava.brq.redhat.com>
References: <1397756352-26694-1-git-send-email-jolsa@redhat.com>
 <1397756352-26694-3-git-send-email-jolsa@redhat.com>
 <1398609395.1689.17.camel@leonhard>
 <20140428100133.GE1109@krava.brq.redhat.com>
 <1398690994.1724.13.camel@leonhard>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <1398690994.1724.13.camel@leonhard>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Apr 28, 2014 at 10:16:34PM +0900, Namhyung Kim wrote:
> 2014-04-28 (월), 12:01 +0200, Jiri Olsa:
> > On Sun, Apr 27, 2014 at 11:36:35PM +0900, Namhyung Kim wrote:
> > > 2014-04-17 (목), 19:39 +0200, Jiri Olsa:
> > > > Keeping the data file description open for the whole life
> > > > of the dso object.
> > > 
> > > I suspect there might be an issue for reporting very large data file
> > > with this approach - like open file limit?
> > 
> > I've got as high as ~200 openned file descriptors for
> > ~2GB data of system wide monitoring
> > 
> > but right that could be an issue.. I wonder we could
> > workaround this somehow, because the speed up is quite
> > noticable
> > 
> > how about we monitor number of openned dso file descriptor
> > and once we cross this we close some portion of them
> > 
> > or something along those lines ;-)
> 
> Yeah, we'll need some way to control those eventually.
> 
> > 
> > > 
> > > 
> > > [SNIP]
> > > > @@ -168,8 +174,8 @@ int dso__data_fd(struct dso *dso, struct machine *machine)
> > > >  	};
> > > >  	int i = 0;
> > > >  
> > > > -	if (dso->binary_type != DSO_BINARY_TYPE__NOT_FOUND)
> > > > -		return open_dso(dso, machine);
> > > 
> > > Why did you remove this line?
> > 
> > that code reopens already openned (and closed) file.. 
> > instead I return (not closed) descriptor from previous open
> 
> But it'll overwrite the dso->binary_type then.  What about this?
> 
> 	if (dso->data_fd >= 0)
> 		return dso->data_fd;
> 
> 	if (dso->binary_type != DSO_BINARY_TYPE__NOT_FOUND) {
> 		dso->data_fd = open_dso(dso, machine);
> 		return dso->data_fd;
> 	}

right, makes sense.. I'll add it with the control code for the
number of openned descriptors

thanks,
jirka