From: Peter Lieven <pl@kamp.de>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: corentincj@iksaif.net, Anthony Liguori <aliguori@us.ibm.com>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 2/3] ui/vnc: optimize dirty bitmap tracking
Date: Mon, 18 Nov 2013 20:55:38 +0100 [thread overview]
Message-ID: <528A70BA.9020002@kamp.de> (raw)
In-Reply-To: <CA+aC4ktm8Csyybrp5g7v33rQOSObsxUkZq8y2m1FkcCaXRvQVQ@mail.gmail.com>
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Am 18.11.2013 17:27, schrieb Anthony Liguori:
>
>
> On Nov 18, 2013 12:20 AM, "Peter Lieven" <pl@kamp.de <mailto:pl@kamp.de>> wrote:
> >
> > vnc_update_client currently scans the dirty bitmap of each client
> > bitwise which is a very costly operation if only few bits are dirty.
> > vnc_refresh_server_surface does almost the same.
> > this patch optimizes both by utilizing the heavily optimized
> > function find_next_bit to find the offset of the next dirty
> > bit in the dirty bitmaps.
> >
> > Signed-off-by: Peter Lieven <pl@kamp.de <mailto:pl@kamp.de>>
>
> Can you include performance data?
>
I hoped that the checking 32bits (pipelined) at once compared to
checking 32bits one-by-one would be convincing enough ;-)
Do you have a special test in mind? Otherwise I could try
to create an artificial test case with e.g. no bits dirty, all bits
dirty, only a few bits dirty (cursor update) and compare the
timing for both versions.
Peter
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next prev parent reply other threads:[~2013-11-18 19:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-18 8:17 [Qemu-devel] [PATCH 0/3] ui/vnc: update optimizations Peter Lieven
2013-11-18 8:17 ` [Qemu-devel] [PATCH 1/3] ui/vnc: introduce VNC_DIRTY_PIXELS_PER_BIT macro Peter Lieven
2013-11-18 8:17 ` [Qemu-devel] [PATCH 2/3] ui/vnc: optimize dirty bitmap tracking Peter Lieven
2013-11-18 16:27 ` Anthony Liguori
2013-11-18 19:55 ` Peter Lieven [this message]
2013-11-19 13:48 ` Peter Lieven
2013-11-19 14:06 ` Peter Lieven
2013-11-18 8:17 ` [Qemu-devel] [PATCH 3/3] ui/vnc: disable adaptive update calculations if not needed Peter Lieven
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