Muli Ben-Yehuda's journal

July 31, 2003

Dave Jones Resurrecting Unmaintained Code

Filed under: Uncategorized — Muli Ben-Yehuda @ 3:36 PM

Thu, 10:00 AM

Listening to Dave Jones talk about resurrecting unmaintained code. This is one of the “fluffier” talks, where it seems to me that it was accepted to OLS more on because of who the speaker is, than because of technical interest. Regardless, Dave is an entertaining speaker. Despite some technical difficulties at the beginning of the talk, it is going rather well.

So far, lots of common sense on how to write maintainable code. For example, write small functions that do one thing well (some of my coworkers should have this tattoo’ed on their foreheads) and “put different functionality in different .c files”. TODO: Code snippets to the contrary of these dictums would make good All Code Sucks posts.

The talk’s examples examples include the MTRR[0] driver and agpgart code.

I spent most of this talk thinking about and writing a “how to port syscalltrack’s system call hijacking code to 2.5”

[0] Documentation/mtrr.txt: “On Intel P6 family processors (Pentium Pro, Pentium II and later) the Memory Type Range Registers (MTRRs) may be used to control processor access to memory ranges. This is most useful when you have a video (VGA) card on a PCI or AGP bus. Enabling write-combining allows bus write transfers to be combined into a larger transfer before bursting over the PCI/AGP bus. This can increase performance of image write operations 2.5 times or more.”

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