From: Steve Kargl <sgk@troutmask.apl.washington.edu>
To: Janne Blomqvist <blomqvist.janne@gmail.com>
Cc: fortran@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: Re: [PATCH,Fortran] Improve PRNG jumping when using threads
Date: Wed, 04 Sep 2019 21:02:00 -0000 [thread overview]
Message-ID: <20190904210218.GA89799@troutmask.apl.washington.edu> (raw)
In-Reply-To: <20190904120926.16851-1-blomqvist.janne@gmail.com>
On Wed, Sep 04, 2019 at 03:09:26PM +0300, Janne Blomqvist wrote:
> Currently, when a new thread needs to use the RANDOM_NUMBER intrinsic,
> the per-thread PRNG state is initialized by copying the master state
> and then jumping forwards N*2**128 entries in the stream so that the
> PRNG streams for different threads don't alias each other, where N is
> the number of threads that have so far initialized the PRNG.
>
> With this patch the master state itself is jumped forwards once each
> time a new thread initializes the PRNG, thus obviating the need to
> jump through all the N-1 previous streams. Effectively turning an O(N)
> algorithm into an O(1) one.
>
> Regtested on x86_64-pc-linux-gnu, Ok for trunk?
>
Ok.
--
Steve
prev parent reply other threads:[~2019-09-04 21:02 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-04 12:09 Janne Blomqvist
2019-09-04 21:02 ` Steve Kargl [this message]
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