Tag: linux

Kernel Debugging at scale

This paper will discuss the difficulties and methods involved in debugging the Linux kernel on huge clusters. Intermittent errors that occur once every few years are hard to debug and become a real problem when running across 1000s of machines simultaneously. The more we scale clusters, the more reliability becomes critical. Many of the normal debugging luxuries like a serial console or physical access are unavailable. Instead, we need a new strategy for addressing thorny intermittent race conditions. This paper presents the case for a new set of tools that are critical to solve these problems and also very useful in a broader context. It then presents the design for one such tool created from a hybrid of a Google internal tool and the open source LTTng project. Real world case studies are included.

how to deal with rare error conditions that are hard to reproduce

Text Rasterization

But it was only a “body show”; the main message of this article is. No more horizontal pixel grid! Really! From now on the horizontal grid is 1/256 of a pixel! You can shift the text horizontally by any fractional value, while the visual appearance does not change a whit! This “little detail” means a lot. How about this:

  • You can kern symbols with sub-pixel precision, not worrying about introducing extra blurriness.
  • You can freely scale the text as you want, with 100% guarantee of preserving a stable text layout that always fits other graphic elements.
  • You can always be sure that the calculated text width exactly corresponds with what you will see on screen and paper.
  • You can apply fancy vector effects such as “faux bold” and “faux italic” being sure the text will not look any blurrier.

there is really no need to still have crappy fonts on all platforms in 2007, as this article superbly demonstrates.