On 3/22/21 2:46 AM, Shu Ming wrote: > More precisely, ss will count partial objects like denty objects with > "/sys/kernel/slab/dentry/partial" whose number can become huge.
Uh, that's interesting. Would you know what exactly it uses the value for? I can think of several reasons why it might be misleading. > On Thu, Mar 18, 2021 at 8:56 PM Xunlei Pang <xlp...@linux.alibaba.com> 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. >
