Wireshark-dev: Re: [Wireshark-dev] one possible way to speed up filtering
From: yami <[email protected]>
Date: Thu, 19 Mar 2009 21:16:43 +0800
Hi Jason,

I think your idea is that we have two threads (virtually, or actually), one is for displaying packets, another for processing all packets. The first thread only processes enough packets for display, such as 3 times of number of packet list pane.

This should be able to improve user experiences, I think. But there may be some issues too. One I can think of is described below.

Wireshark dissectors normally work from the first packet to certain packet. During processing, Wireshark collects important conversation information, such as 'file ID 0x1 is associated to file name hello.txt'.  The display thread may not display these information correctly, since it does not dissect from the very beginning.

On Thu, Mar 19, 2009 at 7:48 PM, Jason <[email protected]> wrote:
yami wrote:
> Thanks, I've written a page in Wiki:
>   http://wiki.wireshark.org/Development/FastFiltering

On a side note, I've had an idea brewing that's along the same lines
that I'll throw out there for comment.

I often work with fairly large capture files (>100MB) and running filter
after filter gets time consuming.

Why not change filtering / packet processing to an "on demand" feature?
 eg. I create a display filter and apply it.  WS then starts at the
current packet position and applies the filter forward and backwards
until it fills the packet list pane with matched packets.  As I move
forwards or backwards through the packet list pane, WS would process a
little more of the file and have a reasonable amount buffered (say one
or two panes full).

If this were carried one step further, and processed packets were freed
once they fell off the packet list pane, huge (multi-gigabyte?) files
could be processed.  A delay would maintain a reasonable buffer in case
the user changed direction.

I'll admit I'm confusing packet processing with packet filtering, but I
think you get the idea.

In the event of reading in a huge file (hundreds of MB to multi GB),
Just process, say, three times the number of packets viewable in the
current packet list pane.

For those concerned about overall stats (like at the bottom of the
window: displayed, filtered, etc), once the above mentioned buffer is
filled, return control to the user and continue processing in the
background at low prio.  A subtle way to let the user know WS is still
applying the filter would be to change "Displayed: 34532" to "Displayed:
35%" until WS finishes and has an exact number.  The percentage could be
either percent processed (100% = finished), or running percentage of
packets processed which match the display filter.

Well, I think I've rambled on long enough.  Thoughts?

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