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Subject: Re: [OMPI devel] thread safety of the self btl
From: Christopher Yeoh (cyeoh_at_[hidden])
Date: 2012-02-08 21:38:57


On Wed, 8 Feb 2012 20:58:52 -0500
George Bosilca <bosilca_at_[hidden]> wrote:

> The self BTL is different from any other BTL. Any memcpy operation
> done by this BTL is automatically protected behind the matching
> logic, and therefore does not require extra thread safety protection.
> A mutex in the self BTL is mostly a copy/paste mistake.
>

So just to clarify, you don't just mean the data source and
destination memory being protected by the matching logic, but
also various linked lists such as self_frags_[eager|send|rdma]
are implicitly protected?

ie. Pretty much need an implicit guarantee that only one thread at a
time will ever call the btl self functions which manipulate those lists.

Regards,

Chris

> george.
>
> On Feb 8, 2012, at 17:57 , Christopher Yeoh wrote:
>
> > Hi,
> >
> > I've noticed that the self btl does not do any locking. It has one
> > lock defined but its not actually used anywhere.
> >
> > So I'm just wondering if that is an oversight or if there is a
> > reason that we know for sure that there will never be concurrent
> > access to that particular btl with threads enabled?
> >
> > Regards,
> >
> > Chris
> > --
> > cyeoh_at_[hidden]
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>
>
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cyeoh_at_[hidden]