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List:       gdb
Subject:    Re: JIT debugging (Attach and speed)
From:       Yichao Yu <yyc1992 () gmail ! com>
Date:       2016-03-24 21:02:08
Message-ID: CAMvDr+QGf+WHgqkkn8Nn8HJ5XqXSMFG60__XZE5=D9Fxs_PE4Q () mail ! gmail ! com
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> There's indeed a huge improvement. The test I was using with ~2000 JIT
> objects goes drops from ~400s to 7.5s (~3s without gdb). However a
> rough scaling test suggests that the scaling is still ~O(n^2) 20k JIT
> objects takes ~500s (~130s without gdb). It seems that the master was
> actually super quadratic (if this is a word) when dealing with
> multiple JIT objects.

The new profile is [1] and it is indeed much closer to the one in 2011.

[1] http://i.imgur.com/K3GKYeq.jpg

>
>> Having a pending breakpoint that is never resolved slows things down
>> significantly again though...  The perf profile shows that breakpoint_re_set
>> ends up calling parse_linespec which wants the selected block, which wants
>> the selected frame, and then we're back at the same...  Maybe we
>> could reconsider how pending breakpoints are re-parsed, and which
>> context they're parsed in.  Not sure.
>>
>> Still, very promising.
>>
>
> Indeed. It's already so much better.

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