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Faster remainders when the divisor is a constant: beating compilers and libdivide

Daniel Lemire

The division by a power of two ( / (2 N )) can be implemented as a right shift if we are working with unsigned integers, which compiles to single instruction: that is possible because the underlying hardware uses a base 2. Thus if 2 N / d has been precomputed, you can compute the division n/d as a multiplication and a shift. Can we do better?

C++ 279
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AWS EC2 Virtualization 2017: Introducing Nitro

Brendan Gregg

Hardware virtualization for cloud computing has come a long way, improving performance using technologies such as VT-x, SR-IOV, VT-d, NVMe, and APICv. The latest AWS hypervisor, Nitro, uses everything to provide a new hardware-assisted hypervisor that is easy to use and has near bare-metal performance. I'd expect between 0.1%

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Back-to-Basics Weekend Reading - A Decomposition Storage Model

All Things Distributed

Not everybody agreed that the "N-ary Storage Model" (NSM) was the best approach for all workloads but it stayed dominant until hardware constraints, especially on caches, forced the community to revisit some of the alternatives. The first practical modern implementation is probably C-Store by Stonebraker, et al.

Storage 72
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The Return of the Frame Pointers

Brendan Gregg

2005-2023: The winter of broken profilers However, the change was then applied to x86-64 (64-bit) as well, which had sixteen registers and didn't benefit so much from a seventeenth. and we may have been flying close to the edge of hardware cache warmth, where adding a bit more instructions caused a big drop.

Java 137
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Why Waits Alone Are Not Enough

SQL Performance

Waits and Queues has been used as a SQL Server performance tuning methodology since Tom Davidson published the above article as well as the well-known SQL Server 2005 Waits and Queues whitepaper in 2006. Since CPU and IO consumption translate directly to server hardware and cloud spend, this is significant. Most Queries Don't Wait.

Tuning 115
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Welcome to the Jungle

Sutter's Mill

Now welcome to the hardware jungle. From 1975 to 2005, our industry accomplished a phenomenal mission: In 30 years, we put a personal computer on every desk, in every home, and in every pocket. In 2005, however, mainstream computing hit a wall. The free lunch is over. Galaxy S II, Droid X2, iPhone 4S). There’s no going back.

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The Credit Cycle Strikes Back

The Agile Manager

Compare that to the relatively robust period of 2005 , when real interest rate curves were positive. Labor productivity improvement was so great compared to the hardware and software costs, interest rates had no discernible effect. In real terms, interest rates are still negative for 5 and 10 year horizons.