Nested CPR patch review

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Nested CPR patch review

Matthew Pickering
Hi all,

I recently resurrected akio's nested cpr branch and put it on
phabricator for review.

https://phabricator.haskell.org/D4244

Sebastian has kindly been going over it and ironed out a few kinks in
the last few days. He says now that he believes the patch is correct.

Is there anything else which needs to be done before merging this patch?

Simon, would you perhaps be able to give the patch a look over?

Cheers,

Matt
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RE: Nested CPR patch review

GHC - devs mailing list
Terrific!

What are the nofib results?

Can we have a couple of artificial benchmarks in cpranal/should_run that show substantial perf improvements because the nested CPR wins in some inner loop?

Is https://ghc.haskell.org/trac/ghc/wiki/NestedCPR still an accurate summary of the idea?   And the Akio2017 sub-page?  It would be easier to review the code if the design documentation accurately described it.

I'll look in the new year.  Thanks!

Simon

|  -----Original Message-----
|  From: Matthew Pickering [mailto:[hidden email]]
|  Sent: 22 December 2017 17:09
|  To: GHC developers <[hidden email]>; Simon Peyton Jones
|  <[hidden email]>; Joachim Breitner <[hidden email]>;
|  [hidden email]; Sebastian Graf <[hidden email]>
|  Subject: Nested CPR patch review
|  
|  Hi all,
|  
|  I recently resurrected akio's nested cpr branch and put it on phabricator
|  for review.
|  
|  https://phabricator.haskell.org/D4244
|  
|  Sebastian has kindly been going over it and ironed out a few kinks in the
|  last few days. He says now that he believes the patch is correct.
|  
|  Is there anything else which needs to be done before merging this patch?
|  
|  Simon, would you perhaps be able to give the patch a look over?
|  
|  Cheers,
|  
|  Matt
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Re: Nested CPR patch review

Matthew Pickering
I don't think anyone has run nofib on the rebased branch yet.

The Akio2017 subpage is a more accurate summary. Sebastian has also
been adding notes to explain the more intricate parts.

Matt

On Fri, Dec 22, 2017 at 5:27 PM, Simon Peyton Jones
<[hidden email]> wrote:

> Terrific!
>
> What are the nofib results?
>
> Can we have a couple of artificial benchmarks in cpranal/should_run that show substantial perf improvements because the nested CPR wins in some inner loop?
>
> Is https://ghc.haskell.org/trac/ghc/wiki/NestedCPR still an accurate summary of the idea?   And the Akio2017 sub-page?  It would be easier to review the code if the design documentation accurately described it.
>
> I'll look in the new year.  Thanks!
>
> Simon
>
> |  -----Original Message-----
> |  From: Matthew Pickering [mailto:[hidden email]]
> |  Sent: 22 December 2017 17:09
> |  To: GHC developers <[hidden email]>; Simon Peyton Jones
> |  <[hidden email]>; Joachim Breitner <[hidden email]>;
> |  [hidden email]; Sebastian Graf <[hidden email]>
> |  Subject: Nested CPR patch review
> |
> |  Hi all,
> |
> |  I recently resurrected akio's nested cpr branch and put it on phabricator
> |  for review.
> |
> |  https://phabricator.haskell.org/D4244
> |
> |  Sebastian has kindly been going over it and ironed out a few kinks in the
> |  last few days. He says now that he believes the patch is correct.
> |
> |  Is there anything else which needs to be done before merging this patch?
> |
> |  Simon, would you perhaps be able to give the patch a look over?
> |
> |  Cheers,
> |
> |  Matt
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Re: Nested CPR patch review

Sebastian Graf
I've since run NoFib. You can find the results here: https://phabricator.haskell.org/D4244#119697

I wonder if you feel that any more notes are needed? The general idea of CPR remained the same, it's just the extension of the DmdResult lattice that needs some rationale as to why and when these new values are needed.

I also wonder what the impact of "Slightly strengthen the strictness analysis" (https://ghc.haskell.org/trac/ghc/wiki/NestedCPR/Akio2017#Changestothedemandanalyzer) would be if regarded in isolation.

On Tue, Jan 2, 2018 at 11:52 AM, Matthew Pickering <[hidden email]> wrote:
I don't think anyone has run nofib on the rebased branch yet.

The Akio2017 subpage is a more accurate summary. Sebastian has also
been adding notes to explain the more intricate parts.

Matt

On Fri, Dec 22, 2017 at 5:27 PM, Simon Peyton Jones
<[hidden email]> wrote:
> Terrific!
>
> What are the nofib results?
>
> Can we have a couple of artificial benchmarks in cpranal/should_run that show substantial perf improvements because the nested CPR wins in some inner loop?
>
> Is https://ghc.haskell.org/trac/ghc/wiki/NestedCPR still an accurate summary of the idea?   And the Akio2017 sub-page?  It would be easier to review the code if the design documentation accurately described it.
>
> I'll look in the new year.  Thanks!
>
> Simon
>
> |  -----Original Message-----
> |  From: Matthew Pickering [mailto:[hidden email]]
> |  Sent: 22 December 2017 17:09
> |  To: GHC developers <[hidden email]>; Simon Peyton Jones
> |  <[hidden email]>; Joachim Breitner <[hidden email]>;
> |  [hidden email]; Sebastian Graf <[hidden email]>
> |  Subject: Nested CPR patch review
> |
> |  Hi all,
> |
> |  I recently resurrected akio's nested cpr branch and put it on phabricator
> |  for review.
> |
> |  https://phabricator.haskell.org/D4244
> |
> |  Sebastian has kindly been going over it and ironed out a few kinks in the
> |  last few days. He says now that he believes the patch is correct.
> |
> |  Is there anything else which needs to be done before merging this patch?
> |
> |  Simon, would you perhaps be able to give the patch a look over?
> |
> |  Cheers,
> |
> |  Matt


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