[parsec-users] Fwd: Swaptions communication

abhisekpan at gmail.com abhisekpan at gmail.com
Wed Oct 30 20:30:08 EDT 2013


Hi Siddharth,

As far as I remember, we saw that the swaption threads use some floating
point libraries (sqrt calls maybe) which do not always declare per-thread
data structures, and hence some data is shared by all threads. I am sorry I
can not be more precise at this point, but you are right in that the code
does not explicitly communicate, and the communication happens through some
library calls. Hope this helps you in some little way!

The way I found this was through the following: dis-assemble the code
(static build), run it in simics, and then compare the logical addresses
which are accessed by more than one cores.

Thanks,
Abhisek


On Wed, Oct 30, 2013 at 7:56 PM, Siddharth Nilakantan <sid.nil at gmail.com>wrote:

> Hi All,
>
> I've been running some multi-core simulations with Swaptions and I've
> noticed that there is thread communication. From looking at the source code
> for swaptions, there should be no communication, as all threads work on
> independent data. Hence, the lack of synchronization primitives as well.
>
> I ran simmedium (32 swaptions), 16 threads and 8 cores. It should divide
> up evenly and there should be no communication at all. These guys also find
> that swaptions has communication:
> http://parsec.cs.princeton.edu/publications/barrow-williams09comm.pdf
>
> Can anyone explain to me why Swaptions exhibits communication?
>
> Regards,
> Siddharth Nilakantan
>
>
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