On Sat, Dec 19, 2020 at 07:48:58PM +0100, Jason A. Donenfeld wrote: > Hi, > > In trying to debug an issue, I came across this text in the config > COMPACTION menu item: > > > Compaction is the only memory management component to form > > high order (larger physically contiguous) memory blocks > > reliably. The page allocator relies on compaction heavily and > > the lack of the feature can lead to unexpected OOM killer > > invocations for high order memory requests. You shouldn't > > disable this option unless there really is a strong reason for > > it and then we would be really interested to hear about that at > > linux-mm@xxxxxxxxx. > > So, here I am as requested. > > My system has 64 gigs of ram. Often times when starting up VMs, with > either QEMU/KVM or with VMware, the VM will be extremely sluggish and > laggy for a little while, usually around 5 minutes. During that phase, > I see kcompact0 using 100% CPU. But other times this doesn't happen at > all. I figured I'd try removing CONFIG_COMPACTION and seeing what > happens, but then I saw your admonishment, so here I am. My initial question is "What is kcompactd doing?" There are a number of tracepoints in kcompactd, so you should be able to enable them all and find out.
