Daniel Lemire's blog AVX-512 gotcha: avoid compressing words to memory with AMD Zen 4 processors
The recent AMD processors (Zen 4) provide extensive support for the powerful AVX-512 instructions. AVX-512 (Advanced Vector Extensions 512) is an extension to the x86 instruction set architecture (ISA) introduced by Intel. These instructions enhance the capabilities of processors by allowing for more data to be processed in parallel. You can process registers made of 64 bytes!
One of the neat trick is that given a mask, you can ‘compress’ words: Suppose that you have a vector made of thirty-two 16-bit words, and you want to only keep the second one and third one, then you can use the vpcompressw instruction and the mask 0b110. It will produce a register where the second and third words are placed in first and second position.
An even nicer trick is that you can use this instruction to write just these two words out to memory. You can invoke this functionality with the _mm_mask_compressstoreu_epi16 function intrinsic.
This works well on recent Intel processors, but not so well on AMD Zen 4 processors.
We have a fast function in the simdjson library to minify a file (remove unnecessary spaces).
Daniel Lemire's blog AVX-512 gotcha: avoid compressing words to memory with AMD Zen 4 processors
The recent AMD processors (Zen 4) provide extensive support for the powerful AVX-512 instructions. AVX-512 (Advanced Vector Extensions 512) is an extension to the x86 instruction set architecture (ISA) introduced by Intel. These instructions enhance the capabilities of processors by allowing for more data to be processed in parallel. You can process registers made of 64 bytes!
One of the neat trick is that given a mask, you can ‘compress’ words: Suppose that you have a vector made of thirty-two 16-bit words, and you want to only keep the second one and third one, then you can use the vpcompressw instruction and the mask 0b110. It will produce a register where the second and third words are placed in first and second position.
An even nicer trick is that you can use this instruction to write just these two words out to memory. You can invoke this functionality with the _mm_mask_compressstoreu_epi16 function intrinsic.
This works well on recent Intel processors, but not so well on AMD Zen 4 processors.
We have a fast function in the simdjson library to minify a file (remove unnecessary spaces).
On December 23rd, 2020, Pavel Durov posted to his channel that the company would need to start generating revenue. In early 2021, he added that any advertising on the platform would not use user data for targeting, and that it would be focused on “large one-to-many channels.” He pledged that ads would be “non-intrusive” and that most users would simply not notice any change. READ MORE Update March 8, 2022: EFF has clarified that Channels and Groups are not fully encrypted, end-to-end, updated our post to link to Telegram’s FAQ for Cloud and Secret chats, updated to clarify that auto-delete is available for group and channel admins, and added some additional links. Multiple pro-Kremlin media figures circulated the post's false claims, including prominent Russian journalist Vladimir Soloviev and the state-controlled Russian outlet RT, according to the DFR Lab's report. Overall, extreme levels of fear in the market seems to have morphed into something more resembling concern. For example, the Cboe Volatility Index fell from its 2022 peak of 36, which it hit Monday, to around 30 on Friday, a sign of easing tensions. Meanwhile, while the price of WTI crude oil slipped from Sunday’s multiyear high $130 of barrel to $109 a pop. Markets have been expecting heavy restrictions on Russian oil, some of which the U.S. has already imposed, and that would reduce the global supply and bring about even more burdensome inflation.
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