Re: Cashe column operations to "end of packet" and only execute the visible ones to save CPU

[Anders Broman <anders.broman () ericsson com>]

-----Original Message-----
> From: wireshark-dev-bounces () wireshark org [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Evan Huus
> Sent: den 11 mars 2014 13:06
> To: Developer support list for Wireshark
> Subject: Re: [Wireshark-dev] Cashe column operations to "end of packet" and only execute the visible ones to save CPU
>
> That sounds like it might be a good idea. Do you have captures where the col_ API is taking a substantial amount of 
> time?

I could probably find something to share privately, not sure if I have something that can be publicly shared, perhaps 
we could profile one of the sample SIP captures?
It was a while since I did the profiling but as I remember the trace had VLAN tags which was costly to no immediate use.

> I expect the most expensive part of the col_ API is probably the formatting calls, but I'm not sure how we'd cache 
> those. I expect we'd have to do the formatting immediately and then cache the >resulting string, so I'm not sure how 
> much benefit that would provide over just formatting in place.

I was hoping someone more familiar with C than me would come up with a way of "cashing the execution" of the function 
:-)
Yes the formatting calls are the expensive ones.

> Worth exploring though.
>
> Evan

On Tue, Mar 11, 2014 at 5:20 AM, Anders Broman <anders.broman () ericsson com> wrote:
> Hi,
>
> How about this idea?
>
> Would it be possible to stack the col..() operations and just execute 
> the relevant ones to save on CPU? Currently we overwrite the data as 
> we work our way through the packet
>
> Until we hit a col_set_fence() then we start to overwrite the stuff 
> after the fence again. One problem might be exceptions - other?
>
>
>
> Best regards
>
> Anders
>
>
>
>
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