How is GNU `yes` so fast?

Re:How is GNU `yes` so fast? by nyanscat on Tuesday June 13, 2017 @09:46AM (#14544647)

from what i can see it's already in a large iovec buffer

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Re:How is GNU `yes` so fast? by mrb on Tuesday June 13, 2017 @09:49AM (#14544659)

Correct, I misread the code. However bumping the pipe size buffer bumps the speed from 28 to 74 GB/s on my Skylake CPU (i5-6500).

Edit: I optimized further and now get 123 GB/s See https://www.reddit.com/r/unix/comments/6gxduc/how_is_gnu_yes...

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Re:How is GNU `yes` so fast? by gpderetta on Tuesday June 13, 2017 @12:24PM (#14545981)

next step is playing tricks with memory mapping so that the buffer is large in virtual memory but only takes a single page in physical memory, fitting in L1 (at least on the read side).

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