23 Feb
2022
23 Feb
'22
5:20 p.m.
在 2/23/2022 4:44 PM, Huang, Ying 写道:
Baolin Wang <baolin.wang(a)linux.alibaba.com>
writes:
We can add a counter for unmapped pages, but it still be little clear
for these cold throttling counter. Please also considering
numa_hint_faults will contain local faults, and some page promotion
counts if the DRAM is free enough.
I think the cold throttling counter is not only for debugging, but also
for doing some decision in future. We can know how many cold pages are
accessed, and we can measure the cold and hot memory distribution for
this workdload to decide if the workload is suitable for the
tiered-memory. So a clear and accurate cold throttling counter will be
helpful. How do you think?
( 2/23/2022 3:51 PM, Huang, Ying S:
Then how about adding a counter for unmapped pages accesses we checked?
And I think these kind of counters are for debugging only at least for
now. Should we merge them formally?
Do you have an example about how to use this new counter or similar one?
Baolin Wang <baolin.wang(a)linux.alibaba.com>
writes:
They are not same. Since numa_hint_faults will not contain file page
promotion statistics, while the should_numa_migrate_memory() will
check the file pages latency before promotion. Here some statistics I
observed:
pgpromote_candidate 3890100
pgpromote_cold_throttle 50342001
numa_hint_faults 35341839
ANBZ: #80
Add page promotion throttle statistic, which can be used to check
how many cold pages were trying to be prmoted to DRAM, and help
to tuning the latency threhold.
Can this be calculated via the following formula?
numa_hint_faults - pgpromote_candidate