Date: Tue, 25 Jan 2022 10:46:20 +0300 From: Victor Gamov <vit@otcnet.ru> To: questions@freebsd.org Subject: Re: snmp oid for memory usage, vmstat -i and others Message-ID: <5e9eb718-0472-fba1-0880-06f539e04790@otcnet.ru> In-Reply-To: <bf5d8bcb-45f7-6829-98f0-10b09e6f6048@aetern.org> References: <bd565507-019d-6fe9-6589-49413e5e1bb6@otcnet.ru> <0c8e1634-d4e2-2ecb-0af4-9f4eceab9124@aetern.org> <bf5d8bcb-45f7-6829-98f0-10b09e6f6048@aetern.org>
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Hi Yuri
Thanks for your reply!
So, I can find total memory via HOST-RESOURCES-MIB::hrMemorySize.0
But how to calculate used memory? I guess I need to find all
HOST-RESOURCES-MIB::hrStorageType = HOST-RESOURCES-TYPES::hrStorageRam
and then multiply corresponding hrStorageAllocationUnits * hrStorageSize
and sum all of them.
Is it correct?
On 25.01.2022 08:32, Yuri wrote:
> Yuri wrote:
>> Victor Gamov wrote:
>>> Hi All
>>>
>>> Some questions about bsnmpd.
>>>
>>> Is it possible to get memory usage via bsnmpd? When I tried to get
>>> something like "snmpget hrStorageDescr.1 hrStorageAllocationUnits.1
>>> hrStorageSize.1 hrStorageUsed.1" then I've got this values:
>>>
>>> =====
>>> HOST-RESOURCES-MIB::hrStorageDescr.1 = STRING: Real Memory Metrics
>>> HOST-RESOURCES-MIB::hrStorageAllocationUnits.1 = INTEGER: 4096 Bytes
>>> HOST-RESOURCES-MIB::hrStorageSize.1 = INTEGER: 391488
>>> HOST-RESOURCES-MIB::hrStorageUsed.1 = INTEGER: 391252
>>> =====
>>>
>>> How I must process it to calculate actual memory usage for machine with
>>> 4GB RAM and without swap?
>>>
>>> =====
>>> $ sysctl hw | egrep 'hw.(phys|user|real)'
>>> hw.physmem: 4243894272
>>> hw.usermem: 3580182528
>>> hw.realmem: 4294967296
>>> =====
>>
>> Values returned by bsnmpd look weird to me as well, so I looked into it
>> a bit. Excerpt from the snmp_hostres (as a standalone test case):
>> ----
>> #include <sys/types.h>
>> #include <sys/sysctl.h>
>> #include <sys/vmmeter.h>
>>
>> #include <vm/vm_param.h>
>>
>> #include <err.h>
>> #include <stdio.h>
>>
>> static struct vmtotal mem_stats;
>>
>> int
>> main(void)
>> {
>> int mib[2] = { CTL_VM, VM_TOTAL };
>> size_t len = sizeof(mem_stats);
>>
>> if (sysctl(mib, 2, &mem_stats, &len, NULL, 0) != 0)
>> err(1, "sysctl");
>>
>> printf("real=%lu\n", mem_stats.t_rm);
>>
>> return (0);
>> }
>> ----
>> output:
>> real=31632
>> ----
>>
>> Now the sysctl output:
>> ----
>> $ sysctl vm.vmtotal
>> vm.vmtotal:
>> System wide totals computed every five seconds: (values in kilobytes)
>> ===============================================
>> Processes: (RUNQ: 1 Disk Wait: 0 Page Wait: 0 Sleep: 28)
>> Virtual Memory: (Total: 547240K Active: 542480K)
>> Real Memory: (Total: 126572K Active: 125600K)
>> Shared Virtual Memory: (Total: 4612K Active: 0K)
>> Shared Real Memory: (Total: 924K Active: 0K)
>> Free Memory: 3608396K
>> ---
>> I can't map the output to anything on the system (16G RAM, 16G swap)
>> except for the "Free Memory", it matches.
>>
>> 31632 ("real") * 4096 ("pagesize") matches the "Real Memory" in sysctl
>> output. Though to get anything resembling 16G, "real" needs to be
>> multiplied by 512 (K?).
>>
>> As a wild guess, it seems that the units used are wrong here, or I
>> simply don't understand the meaning of these values.
>
> Looking at sys/vmmeter.h, my assumptions above are wrong:
>
> uint64_t t_rm; /* total real memory in use */
>
> But that does not include the "wired" (and other) pages, so I'm not sure
> about this metric usefulness.
>
> In any case, you have the following:
>
> HOST-RESOURCES-MIB::hrMemorySize.0 = INTEGER: 16734232 KBytes
>
--
CU,
Victor Gamov
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