potential for controlling memory alignment?
carter.schonwald at gmail.com
Thu Sep 12 20:21:01 UTC 2013
i created a ticket on trac
On Thu, Sep 12, 2013 at 3:46 PM, Carter Schonwald <
carter.schonwald at gmail.com> wrote:
> Reid Barton was just noticing some alignment perf issues and talking
> about it on #ghc / #haskell-llvm
> probably worth documenting it in a ticket!
> On Thu, Sep 12, 2013 at 3:28 PM, Nicolas Frisby <nicolas.frisby at gmail.com>wrote:
>> On my laptop, a program showed a consistent slowdown with -fdicts-strict
>> 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.
>> Can anyone suggest how to validate this hypothesis about misaligned reads?
>> 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.
>> ghc-devs mailing list
>> ghc-devs at haskell.org
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