News for hackers. Stuff that matters.

A comment on How is GNU `yes` so fast?. Parent comment

Re:How is GNU `yes` so fast? by mrb on Tuesday June 13, 2017 @08:44AM (#14544317)
His code can further be optimized by having only 1 large element in the iovec (vs. many 2-byte "y\n" elements).
[ Parent | on HN ]
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
[ Parent | on HN ]
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...

[ Parent | on HN ]
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).
[ Parent | on HN ]