llvm dev - Aug 2007 - [LLVMdev] Tool support for generation of transactional code

I would like to announce the availability of compiler support for generation 
of transactional code in LLVM IR. Our tool is called Tanger and it is an LLVM 
pass. You can download Tanger at: http://tinystm.org

Transactional memory (TM) is viewed by a lot of people to be an important tool 
for enabling parallelism in a wide area of applications, and especially for 
developers that are not skilled in concurrent programming. It is a lot better 
than locking (e.g., w.r.t. composability) and far easier than low-level 
concurrent programming.

Tanger transforms an application that uses a minimal application-level 
declaration API for memory transactions (calls to hook functions begin() and 
commit() to declare transaction boundaries) into an application that contains 
proper calls to an STM for all accesses to memory in transactional code 
(e.g., load instructions are transformed into calls to stm_load() functions). 
You can find a more detailed description in our Transact'07 paper [1]. If
you
use Tanger in your work, please cite this paper (or the paper we link to at 
the website below).

We are looking forward to any comments, questions, and contributions. There is 
large interest in compiler support for transactional memory right now 
especially in the TM community and related communities. I suppose that only 
relatively few people from these communities have a compiler background, so 
we would really like to get support from people that have a compiler 
background.

We thank all the LLVM developers and contributors for creating a great 
compiler framework.


Torvald


[1] Pascal Felber and Christof Fetzer and Ulrich Müller and Torvald Riegel and 
Martin Süsskraut and Heiko Sturzrehm, Transactifying Applications using an 
Open Compiler Framework, TRANSACT, 2007

Torvald,

This is nice work.  Do you have a set of applications or benchmarks  
that you have transactionalized at the source level?  If so, have you  
reported performance numbers for them somewhere?

Thanks,

--Vikram
http://www.cs.uiuc.edu/~vadve
http://llvm.org


On Aug 19, 2007, at 3:22 PM, Torvald Riegel wrote:
> I would like to announce the availability of compiler support for  
> generation
> of transactional code in LLVM IR. Our tool is called Tanger and it  
> is an LLVM
> pass. You can download Tanger at: http://tinystm.org
>
> Transactional memory (TM) is viewed by a lot of people to be an  
> important tool
> for enabling parallelism in a wide area of applications, and  
> especially for
> developers that are not skilled in concurrent programming. It is a  
> lot better
> than locking (e.g., w.r.t. composability) and far easier than low- 
> level
> concurrent programming.
>
> Tanger transforms an application that uses a minimal application-level
> declaration API for memory transactions (calls to hook functions  
> begin() and
> commit() to declare transaction boundaries) into an application  
> that contains
> proper calls to an STM for all accesses to memory in transactional  
> code
> (e.g., load instructions are transformed into calls to stm_load()  
> functions).
> You can find a more detailed description in our Transact'07 paper  
> [1]. If you
> use Tanger in your work, please cite this paper (or the paper we  
> link to at
> the website below).
>
> We are looking forward to any comments, questions, and  
> contributions. There is
> large interest in compiler support for transactional memory right now
> especially in the TM community and related communities. I suppose  
> that only
> relatively few people from these communities have a compiler  
> background, so
> we would really like to get support from people that have a compiler
> background.
>
> We thank all the LLVM developers and contributors for creating a great
> compiler framework.
>
>
> Torvald
>
>
> [1] Pascal Felber and Christof Fetzer and Ulrich Müller and Torvald  
> Riegel and
> Martin Süsskraut and Heiko Sturzrehm, Transactifying Applications  
> using an
> Open Compiler Framework, TRANSACT, 2007
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On Sunday 19 August 2007 22:52, Vikram S. Adve wrote:
> Torvald,
>
> This is nice work.  Do you have a set of applications or benchmarks
> that you have transactionalized at the source level?  If so, have you
> reported performance numbers for them somewhere?
The absence of such a tool is the reason why there are not many benchmarks 
around, especially no applications that are used by real users. There are two 
microbenchmarks in the release and I have performance numbers in my slides 
for the Transact presentation 
(http://wwwse.inf.tu-dresden.de/presentations/slides-felber2007tanger.pdf). 
We currently are not doing any TM-specific optimizations as described in 
recent Intel or MSR papers, but LLVM's generic optimizations seem to be
quite
good at reducing teh number of loads and stores.
I'm currently preparing a Tanger patch for the STAMP benchmarks 
(http://stamp.stanford.edu), but I need to add some features first. A full 
list of the missing features (all, not just for STAMP) that I am aware of is 
in TODO.txt in the release archive.

So, it would be fairly easy to pick, for example, sequential implementations 
of various data structures and run them as transactions, but this is not 
necessarily what users need or how they would use TM. This problem was also 
talked about a lot at Transact's panel discussion, and the agreement was 
roughly that we need real users to be able to evaluate TM correctly.

So we can't give you benchmarks yet, but the idea is that tools such as
Tanger
can make this process much easier, both regarding benchmarks coming from 
researchers and real users. This approach and Tanger are work in progress, 
but we are working on it.
If you have any ideas for benchmarks, or know people that do have and are 
interested in using TM, please tell me.


Torvald