Re: [RFC PATCH v3 00/18] dynamic debug diet plan

[jim . cromie]

On Thu, Mar 18, 2021 at 10:12 PM Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:
>
> Jim Cromie <jim.cromie@xxxxxxxxx> writes:
>
> > CONFIG_DYNAMIC_DEBUG creates a struct _ddebug (56 bytes) for each
> > callsite, which includes 3 pointers to: module, filename, function.
> > These are repetetive, and compressible, this patch series goes about
> > doing that, it:
>
> So how much memory does it actually save?
> -Andi

sorry for late reply, html mode got switched on and I didnt see kickback

on my laptop/build, master has 165kb, about 70k is the compressible data,
RLE column-wize could get close to 60% on my data. so ~40kb ?

3 things to do to get the savings:
figure the compression,
figure the hash holding enabled/used/expanded pr_debug decorations
(maybe optional, depending on indexed/seek decompress time)
drop the site pointer, with some anonymous union struct combo to blend
header with callsites cleanly