On 1/27/21 2:50 PM, Saravanan D wrote: > To help with debugging the sluggishness caused by TLB miss/reload, > we introduce monotonic lifetime hugepage split event counts since > system state: SYSTEM_RUNNING to be displayed as part of > /proc/vmstat in x86 servers > > The lifetime split event information will be displayed at the bottom of > /proc/vmstat > .... > swap_ra 0 > swap_ra_hit 0 > direct_map_2M_splits 167 > direct_map_1G_splits 6 > nr_unstable 0 > .... > > 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. > > Signed-off-by: Saravanan D <saravan...@fb.com> > --- > arch/x86/mm/pat/set_memory.c | 18 ++++++++++++++++++ > include/linux/vm_event_item.h | 8 ++++++++ > mm/vmstat.c | 8 ++++++++ > 3 files changed, 34 insertions(+)
Documenation/ update, please. -- ~Randy
