SystemDependentDataBuffer bits ...
michael.meeks at collabora.com
Fri Apr 26 10:40:34 UTC 2019
I guess you missed the appended on IRC.
It seems odd that just typing in writer should be so rapidly creating
and destroying these cached items. A couple of thoughts:
* do we need to do this for simple / common polylines etc. ?
+ surely there is a complexity/benefit tradeoff here.
* should we not disable the SystemDependentDataBuffer ie.
if(maEntries.empty() && maTimer)
from there we can stop ourselves in the timeout if necessary.
this can save us doing a chunk of un-necesary scheduler work
which can be rather expensive.
Noel any chance of killing those lines & testing ?
Armin - any thoughts on whether this is truly necessary for
simple polylines ? (is it to cache the winding / self
intersection stuff ? )
<mmeeks> caolan, alg: I wonder if you see a lot of:
1556195258227 0x7f0124085af0 restarted a: 1 p: 1 vcl
1556195258227 0x7f0124085af0 stopped a: 1 p: 1 vcl
<mmeeks> caolan: if you run with
<vmiklos> mmeeks: yes, it fies every second, see
<mmeeks> caolan: looks to me like we're doing heavy-lifting to cache
even the cairo paths for the most banal polypolygons we render - (just
typing randomly in writer) - which hits all sorts of locking there, as
well as hitting the scheduler core too.
<mmeeks> vmiklos: sure - but I get ~hundred of those rendering a tile ;-)
<mmeeks> vmiklos: we seem to add and remove it a -lot- which seems
rather unreasonable - but perhaps it's just noisy debuug
<noelgrandin> oddd I thought that that SystemDependantDataBuffer stuff
was only for caching drawing operations for drawinglayer/etc, would not
have expected it to fire in writer
<mmeeks> vmiklos: ~150k of those while typing ~3 lines of random text in
<mmeeks> noelgrandin: might be worth a chase ? =) I suspect we're doing
it for banal polypolygons =)
<mmeeks> and we shouldn't - start/stop/copy/allocate is expensive
<noelgrandin> oh great, debugging SystemDependentDataBuffer::startUsage
<caolan> mmeeks, I don't know anything about that relatively new caching
stuff, except that it seems to be the reason tdf#124863 doesn't work anymore
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