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| Image courtesy of HPE, Inc. |
Computer industry observers, as well as developers have many
questions about this new architecture. This article describes some of the “The
Machine’s” key features. We also attempt to address exactly what this new
system might mean to the industry. We also offer some recommendations on how IT
departments should react to this new system. We do not attempt a deep dive into
the technology. First, a little history.
Von Neumann
Architecture
HPE has been working on its new architecture for several
years. Their goal has been to solve problems posed by the end of the von
Neumann computing era.
Von Neumann architectures were built on the concept of a
central processing unit or CPU. All data reached the relatively fast CPU
through much slower functioning memory. CPU speeds, along with the cost of the
memory itself, meant systems used specialized I/O devices such as tapes, disks,
flash memory etc. to hold the data to be
processed. Until very recently, it was prohibitively expensive to build
memories large enough to hold all the data for processing.
In addition to being cheaper than memory, such I/O devices
were non-volatile. This meant they did not lose all that data when power was
turned off as the memory would. Obviously, losing data along with power,
whether intended (a shutdown) or unintended (power failure, device failure),
was untenable for a working datacenter. Another challenge was the constant
movement of data. Data often comes from a variety of distributed I/O devices,
moves to a central store, and then to computer memory for processing, then
moves back to either storage or another I/O device.
Moore's Law
Moore’s law explains why this architecture worked for the past ½ century. Technically, the law (more precisely an observation) relates to the number of transistors on a chip. It states that this number doubles approximately every 18 months. However, physical limitations appear to mean this law is becoming invalid. (You can’t keep shrinking things indefinitely.) With the law’s end, we can no longer expect microprocessors to drive performance improvement as they have in the past.
However, the requirement for increased processing power
continues to grow, driven in part by the sheer amount of data to be processed.
Other factors driving growth include an increasing number of devices, more
complex data types, the internet of things and an expanding world population.
Studies report that the world’s data doubles every two years, with no sign of
slowing down. The demand for the ability
to process this giant mound of data continues to increase.
The Machine’s
Memory-Driven Architecture
As noted, the center of the von Neumann architecture is the
CPU; large data sets must be split up to fit the relatively small amount of
main memory that is tied to each processor. The much faster, cheaper memory now
on the horizon allows for the emergence of a new architecture with memory at
the center of the system. This new
non-volatile memory (NVM) means data is preserved even if/when power is off.
All data is kept and accessible in greatly expanded memory.
HPE intends to use these emerging NVM technologies to form a
new shared pool of “Fabric-Attached” memory, which means that any processor can
access any byte of data directly, without having to work through another
processor. In addition, this fabric enables processors of many types – x86,
ARM, GPU etc. – to communicate over the same fabric. This allows Memory-Driven
Computing to match a workload with the ideal processor architecture, allowing
tasks to be completed in the shortest possible time using the least amount of
energy. For communication over distances longer than about a foot,
Photonic/Optical communication links are used to allow physical components
spread over a wide area to perform as if they were all located in the same
rack. In addition to improving performance, this delivers breakthrough energy
efficiency and design freedom.
This structure will have several additional immediate
effects. First, it eliminates the requirement for I/O devices in normal
processing. A major cost saving. Next, all data is accessible by normal CPU
instructions. This simplifies application programming with no need to manage
and access data on external devices. Processing speeds increase dramatically as
all data is immediately accessible for processing.
Migration Considerations
A major concern when introducing a new architecture is the difficulty of application migration to the new platform. Since most existing programs were created in a world of limited memory, they will not automatically take advantage of the new architecture. The algorithms that they depend on will have to be rethought to use the larger memories now available. We have had a taste of this type of effort resulting from the recent adoption of in-memory databases.
HPE is trying to make it as easy as possible to get started
by using familiar programming languages and constructs. HPE has invested
considerable resources into the support of the new architecture even to the
extent of creating an optimized version
of Linux[3] running
on a commercial System on a Chip (SOC) which is currently under development by
a partner. They have an extensive program of support and information to help
developers and programmers understand the new environment. This includes
specialized software
tools and services[4].
Structure of the new Datacenter
When fully implemented, the new architecture will drive a
revolution in datacenter design. Full adoption will take many (10-20?)
years. For an extended period,
applications designed for the current technology will have to coexist with the
new architecture apps. Ripping out all the current I/O devices is simply not
possible for numerous reasons, i.e. expense, risk, incompatibilities, poor or
non-existent application documentation, etc. Another factor is the time it
takes to build confidence in a new architecture as developers and other staff work
to acquire expertise and learn its idiosyncrasies.
Performance Considerations
As mentioned above, The Machine’s new architecture offers
the opportunity for many existing applications to be optimized to use what is
essentially unlimited memory. Note that the new architecture does not require
changes to programs, but changes are needed to achieve improved performance.
HPE modified some example code. They reported between 10X to
100X faster performance speeds. These impressive numbers were achieved fairly
easily by optimizing existing algorithms for the larger memory environment.
Further, more radical changes in the algorithms can achieve far greater
speedups. A financial modelling example reported a speedup approaching 10,000X.
However, this involved completely redesigning the application.
The performance story has two sides. On the one hand,
radical change can yield stunning results, as seen in the financial model
example. On the other hand, merely moving an existing unmodified application to
the new environment will not automatically deliver great or, indeed, any
performance improvement.
Economic Considerations
A key factor in determining the speed of new technology
adoption is cost. We lack sufficient data about HPE’s new technology to make
any cost estimates. Obviously, the cost of the new memory will be key. In the
best case, the new technology would be price competitive with, as well as
performance advantaged over existing technology.
A Possible
Action Plan
We think most large IT installations will benefit from
devoting resources and time studying HPE’s new architecture. Here is why. An IT
department wishing to keep its most productive people must demonstrate that
they are forward looking. No one wants to work in an environment where skills
become obsolete because the organization fails to track new technology. This
alone justifies some investment. A second, more compelling reason, is the
potential for immediate payback. Many installations run applications developed
when small memories were common, and where a lack of memory is a major cause of
slow performance. Evaluating applications to assess the potential benefit from
access to large memories can yield significant insights to the potential for
investment payback.
Of course, these efforts must be closely monitored and
controlled. The adage; “If it ain’t
broke don’t fix it” still holds. We are not recommending a major “rip and
replace” mindset. On the other hand, there can be no progress without replacing
old technology. HPE’s “The Machine” has the potential to leverage major
performance improvements in today’s applications. Determining how much to
invest requires a case-by-case evaluation; such effort can be fully justified.
Conclusions
We
applaud HPE’s investments in this architecture. Wisely, they are cultivating a
supportive ecosystem with multiple efforts intended to facilitate access,
educate and involve[5] the
greater IT development community with The Machine. Our conclusions are as follow:
1. The
Machine introduces Memory-Driven Computing which is a radically new
architecture optimized for data-intensive processing.
2. It
effectively addresses problems associated with the collapse of Moore’s Law.
3. The
architecture works and indications are that it can provide impressive (up to
10,000X) performance improvements for a certain spectrum of application types,
when programmed appropriately. Modifying existing applications can yield more
modest, but still substantial, 10X to 100X improvements.
4. HPE
has assembled an impressive array of tools, products and services to encourage
IT staff, especially developers to become familiar with the architecture by
means of easy, inexpensive (sometimes free) access to the technology.
5. We
recommend looking at this technology; it could change your future!
To date, we have seen no other
approach offering as comprehensive a solution to the “end of Moore’s law” dilemma. It will be several years before a final
judgement on this new architecture will be possible. Today, we are optimistic
about HPE’s prospects.
nice blog.
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