Yes skim first. When you start you have no sense of the shape of the topic or what's important. Skimming gives you that information quickly and typically will r

Yes skim first. When you start you have no sense of the shape of the topic or what's important. Skimming gives you that information quickly and typically will reduce the amount of time you spend doing exercises. But skim multiple sources before really committing to one. In your I'd skim K&R plus some other C books, at least two of the giant kernel development books. Then choose something you feel is interesting and challenging enough.