<div dir="ltr">i created a ticket on trac<div><a href="http://ghc.haskell.org/trac/ghc/ticket/8279">http://ghc.haskell.org/trac/ghc/ticket/8279</a><br><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Sep 12, 2013 at 3:46 PM, Carter Schonwald <span dir="ltr"><<a href="mailto:carter.schonwald@gmail.com" target="_blank">carter.schonwald@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr">Reid Barton was just noticing some alignment perf issues and talking about it on #ghc / #haskell-llvm<div>
<br></div><div>probably worth documenting it in a ticket! </div><div><br></div></div><div class="gmail_extra">
<br><br><div class="gmail_quote"><div><div>On Thu, Sep 12, 2013 at 3:28 PM, Nicolas Frisby <span dir="ltr"><<a href="mailto:nicolas.frisby@gmail.com" target="_blank">nicolas.frisby@gmail.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div><div>
<div dir="ltr"><div>On my laptop, a program showed a consistent slowdown with -fdicts-strict</div><div><br></div><div>I didn't find any obvious causes in the Core differences, so I turned to Intel's Performance Counter Monitor for measurements. After trying a few counters, I eventuall saw that there are about an order of magnitude more misaligned memory loads with -fdicts-strict than without, so I think that may be a significant part of the slowdown. I'm not sure if these are code or data reads.</div>
<div><br></div><div>Can anyone suggest how to validate this hypothesis about misaligned reads?</div><div><br></div><div>A subsequent commit has changed the behavior I was seeing, so I'm not interested in alternatives means to determine if -fdicts-strict is somehow at fault — I'm just asking specifically about data/code memory alignment in GHC and how to diagnose/experiment with it.<br>
</div><div><br></div><div><div>Thanks.<br></div><div><br></div><div></div></div>
</div>
<br></div></div>_______________________________________________<br>
ghc-devs mailing list<br>
<a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a><br>
<a href="http://www.haskell.org/mailman/listinfo/ghc-devs" target="_blank">http://www.haskell.org/mailman/listinfo/ghc-devs</a><br>
<br></blockquote></div><br></div>
</blockquote></div><br></div></div></div>