y-cruncher - A Multi-Threaded Pi-Program
From a high-school project that went a little too far...
By Alexander J. Yee
(Last updated: December 3, 2017)
The first scalable multi-threaded Pi-benchmark for multi-core systems...
How fast can your computer compute Pi?
y-cruncher is a program that can compute Pi and other constants to trillions of digits.
It is the first of its kind that is multi-threaded and scalable to multi-core systems. Ever since its launch in 2009, it has become a common benchmarking and stress-testing application for overclockers and hardware enthusiasts.
y-cruncher has been used to set several world records for the most digits of Pi ever computed.
Windows: Version 0.7.4 Build 9478 (Released: December 2, 2017)
Linux : Version 0.7.4 Build 9478 (Released: December 2, 2017)
Official HWBOT thread.
Official XtremeSystems Forums thread.
AV False Positives: (October 24, 2017)
It has come to my attention that the "y-cruncher.exe" launcher binary in Windows has been getting flagged by some virus scanners. This has been the case for at least the last several releases.
This is currently under investigation. Unfortunately, I'm not an expert in this field. So I don't really know what exactly is tripping up the AV heuristics. At this time, the only fix I've found will break compatibility with older versions of Windows.
In case anybody is willing to help, the source code for the launcher binary has been released on GitHub. Compiling it using the provided Visual Studio project will produce the binary that turns up false positive under said virus scanners.
Version 0.7.4: (October 14, 2017)
A new version is out with some changes aimed at addressing the memory bottleneck on Ryzen 7 and Skylake X.
While the changes in this release help alleviate the memory bottleneck, they fall well short of actually solving it. The memory bandwidth problem is here to stay and is expected to get worse if hardware trends continue as they have been for the past decade.
The memory bandwidth problem has actually been an ongoing cat-and-mouse game since the very first version of y-cruncher. Whenever the memory bottleneck catches up in a new generation of hardware, an optimization in y-cruncher is made to push it away again. But it looks like the cat is finally winning on the latest generation of desktop processors - especially the HCC Skylake X line.
y-cruncher has been used to set a number world record size computations.
Blue: Current World Record
Green: Former World Record
Red: Unverified computation. Does not qualify as a world record until verified using an alternate formula.
|Date Announced||Date Completed:||Source:||Who:||Constant:||Decimal Digits:||Time:||Computer:|
|August 24, 2017||August 23, 2017||Ron Watkins||Euler-Mascheroni Constant||477,511,832,674||4 x Xeon E5-4660 v3 @ 2.1 GHz - 1 TB
2 x Xeon X5690 @ 3.47 GHz - 128 GB
|August 14, 2017||August 13, 2017||Ron Watkins||Zeta(3) - Apery's Constant||500,000,000,000||
8 x Xeon 6550 @ 2.0 GHz - 512 GB
2 x Xeon X5690 @ 3.46 GHz - 142 GB
|November 15, 2016||November 11, 2016||Blog
|Peter Trueb||Pi||22,459,157,718,361||Compute: 105 days||4 x Xeon E7-8890 v3 @ 2.50 GHz
1.25 TB DDR4
20 x 6 TB 7200 RPM Seagate
|September 3, 2016||August 29, 2016||Ron Watkins||e||5,000,000,000,000||2 x Xeon X5690 @ 3.47 GHz
|July 11, 2016||July 5, 2016||"yoyo"||Golden Ratio||10,000,000,000,000||
|2 x Intel Xeon E5-2696 v4 @ 2.2 GHz
|June 28, 2016||June 19, 2016||Ron Watkins||Square Root of 2||10,000,000,000,000||2 x Xeon X5690 @ 3.47 GHz
|June 4, 2016||May 29, 2016||Ron Watkins||Lemniscate||250,000,000,000||4 x Xeon E5-4660 v3 @ 2.1 GHz - 1TB
4 x Xeon X6550 @ 2 GHz - 512 GB
|June 4, 2016||June 2, 2016||"yoyo"||Golden Ratio||5,000,000,000,000||
|2 x Intel Xeon E5-2696 v4 @ 2.2 GHz
|April 24, 2016||April 18, 2016||Ron Watkins||Log(2)||500,000,000,000||4 x Xeon X5690 @ 3.47 GHz - 141 GB|
|April 17, 2016||April 12, 2016||Ron Watkins||Catalan's Constant||250,000,000,000||4 x Xeon E5-4660 v3 @ 2.1 GHz
|April 9, 2016||April 3, 2016||Ron Watkins||Log(10)||500,000,000,000||2 x Xeon X5690 @ 3.47 GHz
|February 8, 2016||February 6, 2016||Mike A||Catalan's Constant||500,000,000,000||
|2 x Intel Xeon E5-2697 v3 @ 2.6 GHz
|July 24, 2015||July 22, 2015
July 23, 2015
|Golden Ratio||2,000,000,000,000||4 x Xeon X6550 @ 2 GHz - 512 GB
Xeon E5-2676 v3 @ 2.4 GHz - 64 GB
|October 8, 2014||October 7, 2014||"houkouonchi"||Pi||13,300,000,000,000||2 x Xeon E5-4650L @ 2.6 GHz
192 GB DDR3 @ 1333 MHz
24 x 4 TB + 30 x 3 TB
|December 28, 2013||December 28, 2013||Source||Shigeru Kondo||Pi||12,100,000,000,050||2 x Xeon E5-2690 @ 2.9 GHz
128 GB DDR3 @ 1600 MHz
24 x 3 TB
See the complete list including other notably large computations.
If you wish to set a record, you must run two computations using different formulas (one to compute, the other to verify). Then send me the validation files, but do not make any attempt to modify them. The validation files are protected with a checksum to prevent tampering/cheating. Yes, people have tried to cheat before.
An exception to the "two computations rule" can be made for Pi since it can be verified using BBP formulas.
Note that for anyone attempting to set a Pi world record: Should the attempt succeed, I kindly ask that you make yourself sufficiently available for external requests to access or download the digits in its entirety (at least until it is broken again by someone else). Pi is popular enough that people do actually want to see the digits.
Aside from computing Pi and other constants, y-cruncher is great for stress testing 64-bit systems with lots of ram.
Sample Screenshot: 100 billion digits of Pi
|Core i7 5960X @ 4.0 GHz - 128GB DDR4 @ 2666 MHz - 16 HDs|
Latest Releases: (December 2, 2017)
OS Programs Download Link Size
y-cruncher + HWBOT Submitter
HWBOT Submitter Only
The Linux version comes in both statically and dynamically linked versions. The static version should work on most Linux distributions, but lacks Cilk Plus and NUMA binding. The dynamic version supports all features, but is less portable due to the DLL dependency hell.
The HWBOT submitter allows y-cruncher benchmarks to be submitted to HWBOT - which is a competitive overclocking site. It is currently only available for Windows.
- Windows Vista or later.
- The HWBOT submitter requires the Java 8 Runtime.
- 64-bit Linux is required. There is no support for 32-bit.
- The dynamic version has been tested on Ubuntu 17.04.
- An x86 or x64 processor.
Very old systems that don't meet these requirements may be able to run older versions of y-cruncher. Support goes all the way back to even before Windows XP.
Other Downloads (for C++ programmers):
Comparison Chart: (Last updated: November 9, 2017)
Computations of Pi to various sizes. All times in seconds. All computations done entirely in ram.
The timings include the time needed to convert the digits to decimal representation, but not the time needed to write out the digits to disk.
Laptops + Low-Power:
|Processor(s):||Core i7 3630QM||VIA C46501||Xeon E3-1535M v52||Core i7 6820HK||Pentium N42001|
|Generation:||Intel Ivy Bridge||VIA Isaiah||Intel Skylake||Intel Skylake||Intel Apollo Lake|
|Processor Speed:||3.2 GHz||2.0 GHz||2.9 GHz||3.2 GHz||1.1 - 2.5 GHz|
|Memory:||8 GB - 1600 MHz||16 GB||16 GB||48 GB - 2133 MHz||4 GB|
|Version:||v0.7.2 - AVX||v0.7.2 - AVX||v0.7.1 - ADX||v0.7.4 - ADX||v0.7.2 - SSE4.1|
1Credit to Tralalak.
2Credit to Kaupo Karuse.
|Processor(s):||Core 2 Quad Q6600||Core i7 920||FX-8350||Core i7 4770K||Core i7 5775C1||Core i7 7700K2||Ryzen 7 1800X|
|Generation:||Intel Core||Intel Nehalem||AMD Piledriver||Intel Haswell||Intel Broadwell||Intel Kaby Lake||AMD Zen|
|Processor Speed:||2.4 GHz||3.5 GHz (OC)||4.0 GHz||4.0 GHz (OC)||3.8 GHz (OC)||4.8 GHz (OC)||3.8 GHz|
|Memory:||6 GB - 800 MHz||12 GB - 1333 MHz||32 GB - 1600 MHz||32 GB - 2133 MHz||16 GB - 2400 MHz||64 GB - 3000 MHz||64 GB - 2666 MHz|
|Version:||v0.7.2 - SSE3||v0.7.2 - SSE4.1||v0.7.4 - XOP||v0.7.4 - AVX2||v0.7.1 - ADX||v0.7.1 - ADX||v0.7.4 - ADX|
1Credit to André Bachmann.
2Credit to Oliver Kruse.
|Processor(s):||Core i7 5820K1||Core i7 5960X||Threadripper 1950X2||Core i9 7900X|
|Generation:||Intel Haswell||Intel Haswell||AMD Threadripper||Intel Skylake X|
|Processor Speed:||4.5 GHz (OC)||4.0 GHz (OC)||4.0 GHz (OC)||
|2.4 GHz cache||3.0 GHz cache|
|Memory:||32 GB - 2400 MHz||64 GB - 2400 MHz||128 GB - 2800-3200 MHz||128 GB - 2666 MHz||128 GB - 3800 MHz|
|Version:||v0.7.3 - AVX2||v0.7.4 - AVX2||v0.7.3 - ADX||v0.7.4 - AVX512-DQ|
1Credit to Sean Heneghan.
2Credit to Oliver Kruse.
Due to high core count and the effect of NUMA (Non-Uniform Memory Access), performance on multi-processor systems are extremely sensitive to various settings. Therefore, these benchmarks may not be entirely representative of what the hardware is capable of.
For example, enabling node-interleaving in the BIOS can improve performance by around 2x. But tweaks like these are often not possible as many of these systems corporate or university machines that are heavily locked down and do not provide the user with sufficient access privileges. Furthermore, due the exponentially large space of settings and configurations, it's often difficult to find the optimal set of settings.
|Processor(s):||Xeon X5482||Xeon E5-26901||Xeon E5-2683 v31||Xeon E5-2687W v42||Xeon E5-2696 v43||Xeon E7-8880 v34||Epyc 76015||Xeon Gold 6130F5|
|Generation:||Intel Penryn||Intel Sandy Bridge||Intel Haswell||Intel Broadwell||Intel Broadwell||Intel Haswell||AMD Naples||Intel Skylake Purley|
|Processor Speed:||3.2 GHz||3.5 GHz||2.03 GHz||3.0 GHz||2.2 GHz||2.3 GHz||2.2 GHz||2.1 GHz|
|Memory:||64 GB - 800 MHz||256 GB - ???||128 GB - ???||64 GB||768 GB - ???||2 TB - ???||256 GB - ??||256 GB - ??|
|Version:||v0.7.2 - SSE4.1||v0.6.2/3 - AVX||v0.6.9 - AVX2||v0.7.4 - ADX||v0.7.1 - ADX||v0.7.1 - AVX2||v0.7.3 - ADX||v0.7.3 - AVX512-DQ|
1Credit to Shigeru Kondo.
2Credit to Cameron Giesbrecht.
3Credit to "yoyo".
4Credit to Jacob Coleman.
5Credit to Dave Graham.
I've been asked a few times on what benchmarks quality for these tables. But there aren't any specific rules. For the most part, I try to maximize the variety of processors on the list. So I won't put more than one system in each processor line unless they have drastically different capabilities such as core count. I also have a strong preference for systems that are at the top of their line and have as much memory as possible.
Perhaps the most important part is that the benchmarks are representative of the hardware. If there is any evidence of interference that may cause the hardware to perform suboptimally, they will be excluded. Examples of this include (but are not limited to), underclocking, disabled cores, disabled hyperthreading, disabled AVX, fewer than all memory channels, background programs, thermal throttling, using an outdated version of y-cruncher, etc... Some leeway is given to multi-processor servers since they are so sensitive to numerous factors.
Likewise, absurdly high overclocks will be excluded. These tables are meant to compare systems running at real life speeds. Benchmarks done with extreme overclocks (especially with liquid nitrogen) should go on HWBOT. Just be aware that HWBOT has stringent rules on submissions since it's competitive.
The full chart of rankings for each size can be found here:
These fastest times may include unreleased betas.
Got a faster time? Let me know: email@example.com
Note that I usually don't respond to these emails. I simply put them into the charts which I update periodically.
Because of the memory-intensive nature of computing Pi and other constants, y-cruncher needs a lot of memory bandwidth to perform well. In fact, the program has been noticably memory bound on nearly all high-end desktops since 2012 as well as the majority of multi-socket systems since at least 2006.
Don't be surprised if y-cruncher exposes instabilities that other applications and stress-tests do not. y-cruncher is unusual in that it simultaneously places a heavy load on both the CPU and the entire memory subsystem.
y-cruncher has a lot of settings for tuning parallel performance. By default, it makes a best effort to analyze the hardware and pick the best settings. But because of the virtually unlimited combinations of processor topologies, it's difficult for y-cruncher to optimally pick the best settings for everything. So sometimes the best performance can only be achieved with manual settings.
*These are advanced settings that cannot be changed if you're using the benchmark option in the console UI. To change them, you will need to either run benchmark mode from the command line or use the custom compute menu.
Load imbalance is a faily common problem in y-cruncher. The usual causes are:
This is probably one of the most complicated features in y-cruncher.
Everything in this section is in the process of being re-verified and moved to: https://github.com/Mysticial/y-cruncher/issues
Pi and other Constants:
Hardware and Overclocking:
Here's some interesting sites dedicated to the computation of Pi and other constants:
Contact me via e-mail. I'm pretty good with responding unless it gets caught in my school's junk mail filter.