Physics processing unit: Difference between revisions

Revision as of 03:10, 7 November 2020

Revision as of 22:56, 14 December 2020

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==History==

An early academic PPU research project<ref>S. Yardi, B. Bishop, T. Kelliher, "[http://www.cs.scranton.edu/%7Ebishop/2006acmse.pdf HELLAS: A Specialised Architecture for Interactive Deformable Object Modeling]", ACM Southeast Conference, Melbourne, FL, March 10–12, 2006, pp. 56–61.</ref><ref>B. Bishop, T. Kelliher, "[http://www.cs.scranton.edu/%7Ebishop/TCSVT.ps Specialized Hardware for Deformable Object Modeling]," IEEE Transactions on Circuits and Systems for Video Technology, 13(11):1074–1079, Nov. 2003.</ref> named SPARTA (Simulation of Physics on A Real-Time Architecture) was carried out at Penn State<ref>{{cite web |url=http://www.cse.psu.edu/~mdl/sparta/ |title=SPARTA Homepage |publisher=Cse.psu.edu |accessdateaccess-date=2010-08-16 |url-status=dead |archiveurlarchive-url=https://web.archive.org/web/20100730051043/http://www.cse.psu.edu/~mdl/sparta/ |archivedatearchive-date=2010-07-30 }}</ref> and University of Georgia. This was a simple [[FPGA]] based PPU that was limited to two dimensions. This project was extended into a considerably more advanced [[Application-specific integrated circuit|ASIC]]-based system named HELLAS.

February 2006 saw the release of the first dedicated PPU [[PhysX]] from [[Ageia]] (later merged into [[nVidia]]). The unit is most effective in accelerating [[particle systems]], with only a small performance improvement measured for rigid body physics.<ref>{{cite web|url=http://www.anandtech.com/show/2001/4 |title=Exclusive: ASUS Debuts AGEIA PhysX Hardware |publisher=AnandTech |access-date= |accessdate=2010-08-16}}</ref> The Ageia PPU is documented in depth in their US patent application #20050075849.<ref>{{cite web|url=http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220050075849%22.PGNR.&OS=DN/20050075849&RS=DN/20050075849 |title=United States Patent Application: 0050086040 |publisher=Appft1.uspto.gov |access-date= |accessdate=2010-08-16}}</ref> Nvidia/Ageia no longer produces PPUs and hardware acceleration for physics processing, although it is now supported through some of their graphics processing units.

<gallery class="center" caption="Academic PPU research projects">

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It consists of a general purpose RISC core controlling an array of custom [[SIMD]] floating point [[VLIW]] processors working in local banked memories, with a switch-fabric to manage transfers between them. There is no [[Cache hierarchy|cache-hierarchy]] as in a CPU or GPU.

The PhysX was available from three companies akin to the way [[video card]]s are manufactured. [[ASUS]], [[BFG Technologies]],<ref>{{cite web |url=http://www.bfgtech.com/news_8.31.05.html |title=Archived copy |accessdateaccess-date=2011-06-08 |url-status=dead |archiveurlarchive-url=https://web.archive.org/web/20060426124859/http://www.bfgtech.com/news_8.31.05.html |archivedatearchive-date=2006-04-26 }}</ref> and [[ELSA Technologies]] were the primary manufacturers. PCs with the cards already installed were available from system builders such as [[Alienware]], [[Dell]], and [[Falcon Northwest]].<ref>{{cite magazine | url=https://books.google.com/books?id=mAIAAAAAMBAJ&pg=PA6 | title=BFG Tech ad for the PhysX |magazine=[[Maximum PC]] | date=May 2006 | page=6 | publisher=[[Future US]] | issn=1522-4279 | accessdateaccess-date=2009-09-16}}</ref>

In February 2008, after [[Nvidia]] bought Ageia Technologies and eventually cut off the ability to process PhysX on the AGEIA PPU and NVIDIA GPUs in systems with active ATi/AMD GPUs, it seemed that PhysX went 100% to Nvidia. But in March 2008, Nvidia announced that it will make PhysX an open standard for everyone,<ref>[http://www.custompc.co.uk/news/602205/nvidia-offers-physx-support-to-amd--ati.html Nvidia offers PhysX support to AMD / ATI] {{webarchive|url=https://web.archive.org/web/20080313220419/http://www.custompc.co.uk/news/602205/nvidia-offers-physx-support-to-amd--ati.html |date=2008-03-13 }}</ref> so the main graphic-processor manufacturers will have PhysX support in the next generation graphics cards. Nvidia announced that PhysX will also be available for some of their released graphics cards just by downloading some new drivers.

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===PhysX P1 (PPU) hardware specifications===

[[ASUS]] and [[BFG Technologies]] bought licenses to manufacture alternate versions of AGEIA's PPU, the PhysX P1 with 128&nbsp;MB GDDR3:

* Multi-core device based on the [[MIPS architecture]] with integrated physics acceleration hardware and memory subsystem with "tons of cores"<ref>{{cite web |url=http://www.nvidia.com/object/physx_faq.html |title=PhysX FAQ |publisher=NVIDIA Corporation}}</ref><ref>{{cite web |url=http://www.blachford.info/computer/articles/PhysX2.html |title=Lets Get Physical: Inside The PhysX Physics Processor |publisher= |author=Nicholas Blachford |date=2006}}</ref>

** 125 million [[transistor]]s<ref name="Legit Reviews">[http://www.legitreviews.com/article/346/2/ Legit Reviews - ASUS's AGEIA PhysX P1 Card]</ref>

** 182&nbsp;mm² [[die (integrated circuit)|die]] size

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Havok divides the physics simulation into ''effect'' and ''gameplay'' physics, with effect physics being offloaded (if possible) to the GPU as [[Shader Model 3.0]] instructions and gameplay physics being processed on the CPU as normal. The important distinction between the two is that ''effect'' physics do not affect gameplay (dust or small debris from an explosion, for example); the vast majority of physics operations are still performed in software. This approach differs significantly from the PhysX SDK, which moves all calculations to the PhysX card if it is present.

Since Havok's acquisition by [[Intel]], Havok FX appears to have been shelved or cancelled.<ref name="Shilov2007">{{cite web |title=GPU Physics Dead for Now, Says AMD's Developer Relations Chief |last=Shilov |first=Anton |date=2007-11-19 |accessdateaccess-date=2007-11-26 |publisher=Xbit Laboratories |url=http://www.xbitlabs.com/news/multimedia/display/20071119065621_GPU_Physics_Dead_for_Now_Says_AMD_s_Developer_Relations_Chief.html |url-status=dead |archiveurlarchive-url=https://web.archive.org/web/20111201040726/http://www.xbitlabs.com/news/multimedia/display/20071119065621_GPU_Physics_Dead_for_Now_Says_AMD_s_Developer_Relations_Chief.html |archivedatearchive-date=2011-12-01 }}</ref>

==PPU vs. GPUs==