linux-kernel - Re: [GIT PULL] kdbus for 4.1-rc1

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Date:	Mon, 27 Apr 2015 19:18:04 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Lukasz Skalski <l.skalski@...sung.com>
Cc:	Havoc Pennington <hp@...ox.com>,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Tom Gundersen <teg@...m.no>, Jiri Kosina <jkosina@...e.cz>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Daniel Mack <daniel@...que.org>,
	David Herrmann <dh.herrmann@...il.com>,
	Djalal Harouni <tixxdz@...ndz.org>
Subject: Re: [GIT PULL] kdbus for 4.1-rc1

On Mon, Apr 27, 2015 at 10:57:45AM +0200, Lukasz Skalski wrote:
> On 04/24/2015 09:25 PM, Greg Kroah-Hartman wrote:
> > On Fri, Apr 24, 2015 at 04:34:34PM +0200, Lukasz Skalski wrote:
> >> On 04/24/2015 04:19 PM, Havoc Pennington wrote:
> >>> On Fri, Apr 24, 2015 at 9:50 AM, Lukasz Skalski <l.skalski@...sung.com> wrote:
> >>>> - client: http://fpaste.org/215156/
> >>>>
> >>>
> >>> Cool - it might also be interesting to try this without blocking round
> >>> trips, i.e. send requests as quickly as you can, and collect replies
> >>> asynchronously. That's how people ideally use dbus. It should
> >>> certainly reduce the total benchmark time, but just wondering if this
> >>> usage increases or decreases the delta between userspace daemon and
> >>> kdbus.
> >>
> >> No problem - I'll prepare also asynchronous version.
> > 
> > That would be great to see as well.  Many thanks for doing this work.
> 
> As it was proposed by Havoc and Greg I've created simple benchmark for
> asynchronous calls:
> 
> - server: http://fpaste.org/215157/ (the same as in the previous test)
> - client: http://fpaste.org/215724/ (asynchronous version)
> 
> For asynchronous version of client I had to decrease number of calls to
> 128 (for synchronous version it was x20000 calls), otherwise we can
> exceed the maximum number of pending replies per connection.
> 
> The test results are following:
> 
> +--------------+--------------------+--------------------+
> |              |    Elapsed time    |    Elapsed time    |
> | Message size |  GLIB WITH NATIVE  | GLIB + DBUS-DAEMON |
> |   [bytes]    |    KDBUS SUPPORT*  |                    |
> +--------------+--------------------+--------------------+
> |              |    1) 0.018639 s   |    1) 0.029947 s   |
> |     1000     |    2) 0.017045 s   |    2) 0.032812 s   |
> |              |    3) 0.017490 s   |    3) 0.029971 s   |
> |              |    4) 0.018001 s   |    4) 0.026485 s   |
> +--------------+--------------------+--------------------+
> |              |    3) 0.019898 s   |    3) 0.040914 s   |
> |    10000     |    3) 0.022187 s   |    3) 0.033604 s   |
> |              |    3) 0.020854 s   |    3) 0.037616 s   |
> |              |    3) 0.020020 s   |    3) 0.033772 s   |
> +--------------+--------------------+--------------------+
> *all tests performed without using memfd mechanism.
> 
> And as I wrote in my previous mail, kdbus transport for GLib is not
> finished yet and there are still some places for improvements, so please
> do not treat these test results as final).

Very nice, thanks.  Any chance you can bump those message sizes up to
over 512k?  I think that will show a huge difference.  Even just under
512k should be faster, as you have shown, but I have been told that for
messages larger than 512k, the D-Bus daemon has "issues", which has kept
people from wanting to use messages that large before now.

thanks again,

greg k-h
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