On 1/25/21 12:11 PM, Saravanan D wrote: > Numerous hugepage splits in the linear mapping would give > admins the signal to narrow down the sluggishness caused by TLB > miss/reload. > > One of the many lasting (as we don't coalesce back) sources for huge page > splits is tracing as the granular page attribute/permission changes would > force the kernel to split code segments mapped to huge pages to smaller > ones thereby increasing the probability of TLB miss/reload even after > tracing has been stopped. > > The split event information will be displayed at the bottom of > /proc/meminfo > .... > DirectMap4k: 3505112 kB > DirectMap2M: 19464192 kB > DirectMap1G: 12582912 kB > DirectMap2MSplits: 1705 > DirectMap1GSplits: 20
This seems much more like something we'd want in /proc/vmstat or as a tracepoint than meminfo. A tracepoint would be especially nice because the trace buffer could actually be examined if an admin finds an excessive number of these.
