The Linux kernel has received a significant update to its kernel that has reduced the latency by a factor of around ten. The patch is around 230 LOC and is extremely effective in increasing system responsiveness under heavy load conditions.
The code achieves this by grouping together task under the same TTY (terminal type) to increase interactivity. Mike Galbraith has written the code, which is already in its third version, while Linus Torvalds himself inspired the idea.
Mike Galbraith carried out some tests to see that the latency in average conditions dropped around 60 times and around 10 times in maximum load conditions. Linus writes in an email response saying,
It’s an improvement for things like smooth scrolling around, but what I found more interesting was how it seems to really make web pages load a lot faster. Maybe it shouldn’t have been surprising, but I always associated that with network performance. But there’s clearly enough of a CPU load when loading a new web page that if you have a load average of 50+ at the same time, you _will_ be starved for CPU in the loading process, and probably won’t get all the http requests out quickly enough.
So I think this is firmly one of those “real improvement” patches. Good job. Group scheduling goes from “useful for some specific server loads” to “that’s a killer feature”.