Hi list! Whenever I do sequential IO for a long stretch of time (e.g. md5summing 40 GB), I'm experiencing high load (ca. 6 on a 4 CPU system) and temporary freezes of most applications. For example, switching between tabs in konsole sometimes takes more than 2 seconds.
When doing this on an ext4 filesystem, the load seems to result from khugepaged and kswapd0 as well as some kworkers. I think I've had similar issues with NFS over wifi but I cannot test this now. Today I copied 60GB from my hard disk to an USB disk formatted with NTFS, issuing the copy command from KDE's dolphin. The freezes became so long it was impossible to work and then X11 locked up and had to be killed. I tried using a preemptive kernel but that didn't seem to help. blkio and cpu cgroups didn't help either. Ionice seems to be the only solution but while I'm okay with that, my dad won't be. Can anyone tell me what is causing this behavior? Throughput is good, by the way. That's why I don't suspect a driver issue. Thanks in advance! Florian Philipp
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