How's the integration of DWARF support coming along?
johan.tibell at gmail.com
Wed Aug 13 18:01:04 UTC 2014
What's the minimal amount of work we need to do to just get the dwarf data
in the codegen by 7.10 (RC late december) so we can start using e.g. linux
perf events to profile Haskell programs?
On Wed, Aug 13, 2014 at 7:31 PM, Arash Rouhani <rarash at student.chalmers.se>
> Hi Johan!
> I haven't done much (just been lazy) lately, I've tried to benchmark my
> results but I don't get any sensible results at all yet.
> Last time Peter said he's working on a more portable way to read dwarf
> information that doesn't require Linux. But I'm sure he'll give a more
> acurate update than me soon in this mail thread.
> As for stack traces, I don't think there's any big tasks left, but I
> summarize what I have in mind:
> - The haskell interface is done and I've iterated on it a bit, so it's
> in a decent shape at least. Some parts still need testing.
> - I wish I could implement the `forceCaseContinuation` that I've
> described in my thesis. If someone is good with code generation (I just
> suck at it, it's probably simple) and is willing to assist me a bit, please
> say so. :)
> - I tried benchmarking, I gave up after not getting any useful results.
> - I'm unfortunately totally incapable to help out with dwarf debug
> data generation, only Peter knows that part, particularly I never grasped
> his theoretical framework of causality in Haskell.
> - Peter and I have finally agreed on a simple and sensible way to
> implement `catchWithStack` that have all most good properties you would
> like. I just need to implement it and test it. I can definitely man up and
> implement this. :)
> Here's my master thesis btw , it should answer Ömer's question of how
> we retrieve a stack from a language you think won't have a stack. :)
> : http://arashrouhani.com/papers/master-thesis.pdf
> On 2014-08-13 17:02, Johan Tibell wrote:
> How's the integration of DWARF support coming along? It's probably one
> of the most important improvements to the runtime in quite some time since
> unlocks *two* important features, namely
> * trustworthy profiling (using e.g. Linux perf events and other
> low-overhead, code preserving, sampling profilers), and
> * stack traces.
> The former is really important to move our core libraries performance up
> a notch. Right now -prof is too invasive for it to be useful when
> evaluating the hotspots in these libraries (which are already often heavily
> The latter one is really important for real life Haskell on the server,
> where you can sometimes can get some crash that only happens once a day
> under very specific conditions. Knowing where the crash happens is then
> *very* useful.
> -- Johan
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