seven things tagged “references”

Latency Numbers “Every Programmer Should Know”

From a presentation by Jeff Dean. What about when technology evolves? Here’s a handy visualization. And here’s a way to think about these numbers. Nathan Hurst visualized the distances on Google Maps1.

Operation Time (ns) Light Distance (m) Approximate Light Distance
L1 cache reference 0.5 0.15 Diagonal across your smartphone
Branch mispredict 5 1.5 Height of Natalie Portman
L2 cache reference 7 2.1 Height of Shaq
Mutex lock/unlock 25 7.5 Height of a school flag pole
Main memory reference 100 30 Half a Manhattan city block (North/South)
Compress 1K bytes with Zippy 3,000 900 Width of Central Park
Send 1K bytes over 1 Gbps network 10,000 3,000 Width of Manhattan
Read 4K randomly from SSD* 150,000 45,000 NYC to Hempstead on Long Island
Read 1 MB sequentially from memory 250,000 75,000 NYC to Princeton/Trenton, NJ
Round trip within same datacenter 500,000 150,000 NYC to Scranton, PA
Read 1 MB sequentially from SSD* 1,000,000 300,000 NYC to Boston, MA
Disk seek 10,000,000 3,000,000 NYC to Austin, TX
Read 1 MB sequentially from disk 20,000,000 6,000,000 NYC to Paris, France (also the diameter of the Earth)
Send packet CA → Netherlands → CA 150,000,000 45,000,000 Once around the equator

  1. Cached: One, Two, Three. ↩︎

Guide to Book Conditions

Reproduced here via AbeBooks with this caveat:

The definitions below are for reference only. Booksellers use these terms, as well as unique terms not included in this list, based on their own criteria. If you would like clarification on any term in a particular seller’s description, please contact the bookseller directly for further information.

Condition Description
As New The book is in the same immaculate condition as when it was published. This could be the description for a book that has been lost in a warehouse for years, never shelved, thumbed or even opened yet may still be some years old.
Fine (F or FN) A Fine book approaches the condition of As New, but without being crisp. The book may have been opened and read, but there are no defects to the book, jacket or pages.
Very Good (VG) Describes a book that shows some small signs of wear - but no tears - on either binding or paper. Any defects should be noted by the seller.
Good (G) Describes the average used worn book that has all pages or leaves present. Any defects should be noted by the seller.
Fair Worn book that has complete text pages (including those with maps or plates) but may lack endpapers, half-title, etc. (which must be noted). Binding, jacket (if any), etc., may also be worn. All defects should be noted.
Poor Describes a book that is sufficiently worn. Any missing maps or plates should still be noted. This copy may be soiled, scuffed, stained or spotted and may have loose joints, hinges, pages, etc.
Binding Copy describes a book in which the pages or leaves are perfect but the binding is very bad, loose, off, or nonexistent.
Reading Copy A copy usually in poor to fair condition that includes all text presented in a legible fashion. The copy is fine to read but nothing more.

Other Descriptors used in Conjunction with the Above Grading Scale

Term Meaning
Bowed A condition of the covers or boards of a hard cover book. Bowed covers may turn inward toward the leaves or outward away from the leaves. The condition generally results from a rapid change in the level of moisture in the air and is caused by different rates of expansion or contraction of the paste-down and the outer material covering the board.
Chipped Used to describe where small pieces are missing from the edges of the boards or where fraying has occurred on a dust jacket or the edge of a paperback.
Dampstained A light stain on the cover or on the leaves of a book caused by moisture such as a piece of food or perspiration. Generally not as severe as waterstains.
Darkening or Fading When book covers are exposed to light, the color darkens or becomes more intense. See also tape shadow.
Edgeworn Wear along the edges of hardback book covers.
Ex-library the book was once owned by, and circulated in, a public library. This book could well be in any of the above general categories but more often than not has been well used. May have library stickers, stamps, or markings. Any former library book must be marked ex-library.
Foxed / Foxing Brown spotting of the paper caused by a chemical reaction, generally found in 19th century books, particularly in steel engravings of the period.
Loose The binding of a new book is very tight; that is, the book will not open easily and generally does not want to remain open to any given page. As the book is used, the binding becomes looser until a well-used book may lay flat and remain open to any page in the book.
Made-up Copy A copy of a book whose parts have been assembled from one or more defective copies.
Price Clipped The price has been clipped from the corner of the dust jacket.
Re-backed A book that has been repaired by replacing the spine and mending the hinges.
Re-cased A book that has been glued back into its covers after having been shaken loose.
Re-jointed Means the book has been repaired preserving the original covers, including the spine.
Shaken An adjective describing a book whose pages are beginning to come loose from the binding.
Shelf Wear The wear that occurs as a book is placed onto and removed from a shelf. It may be to the tail (bottom) edge of the covers as they rub against the shelf, to the dust jacket or exterior of the covers (when no dust jacket is present) as the book rubs against its neighbors, or to the head of the spine which some use to pull the book from the shelf.
Sunned Faded from exposure to light or direct sunlight.
Tight The binding of a new book is very tight; that is, the book will not open easily and generally does not want to remain open to any given page. As the book is used, the binding becomes looser until a well-used book may lay flat and remain open to any page in the book.
Trimmed An adjective indicating that the pages have been cut down to a size smaller than when originally issued.
Unopened The leaves of the book are still joined at the folds, not slit apart.
Working copy Even more damaged than a reading copy, the working copy will have multiple defects and may even need repair.
Worming, Wormholes Small holes resulting from bookworms (the larvae of various beetles.)

A List of Hacker News ‘Classics’

When you’re following a bunch of feeds, it’s easy to forget that the web is the greatest library in the history of the world—and that a good library doesn’t just have a rack of newspapers, it has a vast collection of books and archives: the stacks.

These are stories that get reposted a lot. Many of them truly are classics.

Getting Naticked

Rex Parker:

A long time ago, I was solving this puzzle and got stuck at an unguessable (to me) crossing: N. C. WYETH crossing NATICK at the “N” — I knew WYETH but forgot his initials, and NATICK… is a suburb of Boston that I had no hope of knowing. It was clued as someplace the Boston Marathon runs through (???). Anyway, NATICK — the more obscure name in that crossing — became shorthand for an unguessable cross, esp. where the cross involves two proper nouns, neither of which is exceedingly well known. NATICK took hold as crossword slang, and the term can now be both noun (“I had a NATICK in the SW corner…”) or verb (“I got NATICKED by 50A / 34D!”)

Here’s the Urban Dictionary entry. Learned that that “crosswordese” is a thing. Been doing the NYT Crosswords fairly regularly over the past few years and that page has a lot of useful, vowel-y ‘bridge’ words and phrases (e.g. AGRA, ESAU, ISAO, OMOO, DEUSIRAE.)