But Chinese scientists have become more secretive as the U.S. has tried to hinder China’s technological progress, and they have stopped participating altogether in a prominent international supercomputing forum.
The
withdrawal marked the end of an era and created a divide that Western
scientists say will slow the development of AI and other technologies as
countries pursue separate projects.
The
new secrecy also makes it harder for the U.S. government to answer a
question it deems essential to national security: Does the U.S. or China
have faster supercomputers? Some academics have taken it upon
themselves to hunt for clues about China’s supercomputing progress,
scrutinizing research papers and cornering Chinese peers at conferences.
Supercomputers have become central to the U.S.-China technological Cold War
because the country with the faster supercomputers can also hold an
advantage in developing nuclear weapons and other military technology.
“If
the other guy can use a supercomputer to simulate and develop a fighter
jet or weapon 20% or even 1% better than yours in terms of range, speed
and accuracy, it’s going to target you first, and then it’s checkmate,”
said Jimmy Goodrich, a senior adviser for technology analysis at Rand Corp., a think tank.
The
forum that China recently stopped participating in is called the
Top500, which ranks the world’s 500 fastest supercomputers. While the
latest ranking, released in June, says the world’s three fastest
computers are in the U.S., the reality is probably different.
“The Chinese have machines that are faster,” said Top500 co-founder Jack Dongarra. “They just haven’t submitted the results.”
Today’s fastest supercomputers are powered by tens of thousands of cutting-edge computer chips. A 2015 U.S. move curtailed Chinese supercomputer developers’ access to Intel chips and other U.S. hardware, followed by broader export restrictions four years later under the Trump administration. The Biden administration has tightened them further.
Dongarra
and analysts who study China said they believed Beijing was worried the
U.S. might do even more if China bragged about its supercomputing
abilities.
They
said it would be difficult for China to maintain its lead in
supercomputing without leading-edge chips, many of them made by Silicon
Valley leader Nvidia.
Without those chips, China would have to use a brute-force workaround
by stringing together hundreds of thousands of older-generation chips
that gobble power.
In
the age of artificial intelligence, limited access to high-end chips
would force China to pick and choose what its supercomputers focus on,
Goodrich said.
The rise of Chinese supercomputers
Supercomputing
dates back to the 1960s, when U.S. government agencies started to
design machines for juggling huge amounts of data simultaneously to
solve problems in a way that less powerful computers working separately
couldn’t match easily. The purposes were similar to today: simulating a
nuclear-weapon detonation, modeling the climate and solving other big
scientific problems.
The
Top500 was born in 1993 when Dongarra, a University of Tennessee
professor, and German colleagues distributed a math problem for
supercomputers, and then ranked the machines by how long they took to
solve it.
Participating
in the list has always been voluntary. Dongarra estimates there are
about 50 supercomputers, including those owned by intelligence agencies
or private companies, that would make the Top500 if their owners
submitted data.
For more than two decades, U.S. machines led the ranking,
issued twice a year. But by November 2017, China had 202 machines on
the list, compared with 143 for the U.S. “China dominated,” crowed
Beijing’s state news agency at the time.
In
2019, the U.S. Commerce Department put five Chinese supercomputing
organizations on a blacklist, saying they used supercomputers for
military and nuclear purposes. The sanctions banned U.S. companies from
selling components to those organizations without a license.
“It
was a major turning point,” said Dongarra. Participation in the list
dwindled. When he asked Chinese colleagues why, they said they weren’t
allowed to submit information, Dongarra recalled. Chinese scientists
also reduced how much data they shared in other scientific forums.
Chinese
government agencies have led supercomputer development, with relatively
few commercially operated machines. These government bodies have
highlighted how the latest Chinese models use domestically produced
processors, now that those from Intel and other U.S. companies are less
accessible.
Chinese
government and science officials didn’t respond to requests for
comment. A spokeswoman for the U.S. Commerce Department, which
implements the supercomputing export controls, referred to previous
statements by the agency that said the controls address
national-security threats posed by China.
A new frontier
Officially,
the fastest computer on the Top500 sits at the Energy
Department-sponsored Oak Ridge National Laboratory, in Tennessee. Called
Frontier,
it is about the size of two tennis courts, cost $600 million to
construct and has an electricity bill of about $20 million a year, said
Dongarra, who also works at Oak Ridge. It uses tens of thousands of
computer chips.
Dongarra
doesn’t think Frontier is actually the world’s fastest supercomputer.
Scientific papers suggest that certain Chinese machines are better. One
has been referred to in state media as a prototype Tianhe-3, after a
Chinese term for the Milky Way galaxy, while the other is a model in the
Sunway series of supercomputers.
The
Chinese papers describe the processors in the machines, what
applications they run and the results they get, giving a good estimate
of how fast the supercomputers are, Dongarra said.
A
scientific paper submitted last year for the Gordon Bell
Prize—essentially the Oscars of supercomputing—described the Sunway
supercomputer as having 39 million cores, or parts of the chips that
carry out processing. That is quadruple the number of cores Frontier
has. Combined with other clues, that statistic indicates that the Sunway
machine may be more powerful than Frontier.
China
produces its own “best of” list for high-performance computing, which
it calls the HPC Top100. Dongarra said he believed it left out leading
Chinese supercomputers.
The
No. 1 machine on the latest Top100 and some others are described in
only generic terms without a name or operating institution given. Last
December, a month after the latest list was released, the National
Supercomputing Center in Guangzhou introduced a machine called Tianhe
Xingyi, saying it achieved a manifold increase in performance over an
earlier model in the Milky Way series called Tianhe-2.
Besides
reading the papers, Dongarra tries to confirm the specifications in a
more old-fashioned way: by attending presentations by Chinese scientists
at conferences and peppering them with questions afterward.
“That’s
sort of my verification: When I talk to them, it’s clear that they have
such a machine,” he said, referring to the computers he believes are
actually the world’s fastest.
Write to Stu Woo at Stu.Woo@wsj.com