[parsec-users] Fwd: Swaptions communication

Siddharth Nilakantan sid.nil at gmail.com
Fri Nov 8 12:18:46 EST 2013


Hi all,

Very sorry for the late response. I didn't get an explicit reply in my mail
inbox, but rather a digest version of daily mails and I missed your
responses.

Kishore,

I think Abhisek answered your question. I saw communication between all
threads. The paper I linked to, has a thread communication pattern in
Figure 5. Take a look at that.

Abhisek,

Thanks for the info. How did you narrow in on the function names that the
addresses were accessed under? Am I correct in assuming that these library
calls are executed in kernel mode? The simulation framework I am using does
not have visibility into what happens in the kernel. I wonder how Gem5's SE
mode would handle such calls. Would it do the appropriate locking.

Sid


On 31 October 2013 12:00, <parsec-users-request at lists.cs.princeton.edu>wrote:

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>    1. Fwd: Swaptions communication (Siddharth Nilakantan)
>    2. Re: Fwd: Swaptions communication (kishore kumar)
>    3. Re: Fwd: Swaptions communication (abhisekpan at gmail.com)
>
>
> ---------- Forwarded message ----------
> From: Siddharth Nilakantan <sid.nil at gmail.com>
> To: parsec-users at lists.cs.princeton.edu
> Cc:
> Date: Wed, 30 Oct 2013 19:56:32 -0400
> Subject: [parsec-users] Fwd: Swaptions communication
> 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
>
>
>
> ---------- Forwarded message ----------
> From: kishore kumar <kishoreguptaos at gmail.com>
> To: PARSEC Users <parsec-users at lists.cs.princeton.edu>
> Cc:
> Date: Wed, 30 Oct 2013 17:09:28 -0700
> Subject: Re: [parsec-users] Fwd: Swaptions communication
> Hi Siddharth,
>
> How do you find that there is a communication between threads? Which data?
>
> Best,
> Kishore Kumar Pusukuri
> http://www.cs.ucr.edu/~kishore
>
>
> On Wed, Oct 30, 2013 at 4:56 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
>>
>>
>> _______________________________________________
>> parsec-users mailing list
>> parsec-users at lists.cs.princeton.edu
>> https://lists.cs.princeton.edu/mailman/listinfo/parsec-users
>>
>>
>
>
> ---------- Forwarded message ----------
> From: "abhisekpan at gmail.com" <abhisekpan at gmail.com>
> To: PARSEC Users <parsec-users at lists.cs.princeton.edu>
> Cc:
> Date: Wed, 30 Oct 2013 20:30:08 -0400
> Subject: Re: [parsec-users] Fwd: Swaptions communication
> 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
>>
>>
>> _______________________________________________
>> parsec-users mailing list
>> parsec-users at lists.cs.princeton.edu
>> https://lists.cs.princeton.edu/mailman/listinfo/parsec-users
>>
>>
>
>
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