Sometimes my computer became unresponsive and couldn’t do any action while copying to slow USB Keys. I found online the reason and the solution to this.
Apparently the configuration /sys/kernel/mm/transparent_hugepage/khugepaged/defrag can really influence this issue. If it’s set to “always” the machine will try to defragment pages to have space for huge pages.
Setting it to “madvise” will active the behavior only on address spaces that require it without interfering with the feature (disabling it) ,still allowing HugePages aware applications to use them, and, espescially, will stop your machine from hanging.
As state in a Phoronix article linked at the bottom of the page since Kernel 3.8 this feature avoids allocating huge chunks of memory when not necessary, so maybe setting /sys/kernel/mm/transparent_hugepage/khugepaged/enabled to “always” may be a good idea after all.
Here you can read more about the HugePages support
Here you can see some benchmarks