Comment 79 for bug 317781

@Michael,

The trick is being able to determine which applications are being too aggressive with writing files. Section 5 in the laptop-mode's FAQ: http://samwel.tk/laptop_mode/faq has some good tips about how to detect which applications are writing indiscriminately to the disk. However, some amount of work will be necessary to determine how much writing the applications are doing, and whether it is "justified" or "unjustified". What we really need is a powertop-like program that tracks write and inode activity so that application writers can be shamed into fixing their applications.

"echo 1 > /proc/sys/vm/block_dump" works, but unfortunately you have to shutdown sysklogd first, and it doesn't summarize information very well. Ideally we also would also track fsync vs. fdatasync calls. Creating a custom ftrace module in the kernel plus a userspace application and then promulgating it as the next step in trying to reduce battery usage and promote SSD friendly applications is probably what we need to do.

My concern with encouraging people to file bugs against applications is whether or not people will accurately file j'accuse! statements against the correct applications. If there are too many false positives and/or false negatives, it might end up being counterproductive. The advantage of creating a powertop-like tool is once you have something which can measured, application authors have something they can optimize against --- and as they old saying goes, you get what you measure.