More precisely, ss will count partial objects like denty objects with "/sys/kernel/slab/dentry/partial" whose number can become huge. On Thu, Mar 18, 2021 at 8:56 PM Xunlei Pang <xlpang@xxxxxxxxxxxxxxxxx> wrote: > > > > On 3/18/21 8:18 PM, Vlastimil Babka wrote: > > On 3/17/21 8:54 AM, Xunlei Pang wrote: > >> The node list_lock in count_partial() spends long time iterating > >> in case of large amount of partial page lists, which can cause > >> thunder herd effect to the list_lock contention. > >> > >> We have HSF RT(High-speed Service Framework Response-Time) monitors, > >> the RT figures fluctuated randomly, then we deployed a tool detecting > >> "irq off" and "preempt off" to dump the culprit's calltrace, capturing > >> the list_lock cost nearly 100ms with irq off issued by "ss", this also > >> caused network timeouts. > > > > I forgot to ask, how does "ss" come into this? It displays network connections > > AFAIK. Does it read any SLUB counters or slabinfo? > > > > ss may access /proc/slabinfo to acquire network related slab statistics.
