Comment 673 for bug 595047

I'm curious: this bug was ostensibly fixed years ago however I dare everyone, who owns an Android smartphone, run a simple test. Invoke any terminal emulator and execute this command:

$ cat < /dev/zero > /sdcard/EMPTY

What's terribly unpleasant is that _all_ CPU cores become busy (more than 75% load), and the CPU jumps into the highest performance state, i.e. frequency, i.e. power consumption. Obviously this is wrong, bad and shouldn't happen. This test is kinda artificial as no Android app can create such a high IO load, but then there are multiple phones out there with either 5GHz MIMO 802.11n or 802.11ac chips which allow up to 80MB/sec throughput which can easily saturate most if not all internal MMC cards and have the same effect as the above command.

Perhaps vanilla kernel bugzilla is not a place to discuss bugs in Android, but latest Android releases usually feature kernels 3.10.x and 4.1.x without that many patches, so this bug is still there. Both these kernels are currently maintained and supported. Android by default never uses SWAP (one of the reasons for this bug).

Go figure.

P.S. Sample apps from Google Play:

* CPU Stats by takke
* Terminal Emulator by Jack Palevich