threez/ruby-vmstat

Vmstat.snapshot.memory different from free

Closed this issue · 9 comments

sithara commented

Hi

My Vmstat.snapshot.memory and free is showing huge different. Could you please help understand the difference between them ? How do I find total memory with ruby-vmstat?

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Adding the output of vmstat -s

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Thanks

threez commented

Hi, please see #4 any re-open if that doesn't answer your question.

sithara commented

@threez I had gone through that but I couldn't get the fact that how is there so much difference? Also how can I compute the total memory? Also why does the values differ so much from vmstat-s

threez commented

Does this help you? #24 (comment)

It depends on what you want so way, I know that is not helpful ;-). If you are on linux you may want to use available to check on the available memory, on most other operating systems you may want to ((wired + active + inactive).to_f / total) * 100.0 to get use memory or use (free.to_f / total) * 100.0 for free.

sithara commented

I'm on azure ubuntu 18 VM, I was trying to figure out the total memory. From the ruby library I've got close to only 12gb(adding active+wired+inactive+free) where as from vmstat -s and free -m its 47gb 😕

threez commented

What system are you working with?

sithara commented

Ror application with redis server set up on szure ubuntu vm.With htop there is 27gb free m/y available, 18gb used by redis

threez commented

Could you provide the contents of /proc/meminfo that is the infomration that is used to provide you with the memory details.

sithara commented

cat /proc/meminfo

MemTotal:       32916912 kB
MemFree:        27821984 kB
MemAvailable:   29327948 kB
Buffers:          213048 kB
Cached:          1535592 kB
SwapCached:            0 kB
Active:          3297804 kB
Inactive:         986192 kB
Active(anon):    2535864 kB
Inactive(anon):     1076 kB
Active(file):     761940 kB
Inactive(file):   985116 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:             0 kB
SwapFree:              0 kB
Dirty:               996 kB
Writeback:             0 kB
AnonPages:       2528852 kB
Mapped:           184160 kB
Shmem:              1596 kB
KReclaimable:     233736 kB
Slab:             437576 kB
SReclaimable:     233736 kB
SUnreclaim:       203840 kB
KernelStack:        9376 kB
PageTables:        17604 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    16458456 kB
Committed_AS:    4609044 kB
VmallocTotal:   34359738367 kB
VmallocUsed:           0 kB
VmallocChunk:          0 kB
Percpu:            89088 kB
HardwareCorrupted:     0 kB
AnonHugePages:   2232320 kB
ShmemHugePages:        0 kB
ShmemPmdMapped:        0 kB
CmaTotal:              0 kB
CmaFree:               0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
Hugetlb:               0 kB
DirectMap4k:      268224 kB
DirectMap2M:     8120320 kB
DirectMap1G:    27262976 kB

free -m

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Vmstat.snapshot.memory

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threez commented

That looks fine to me, did you notice that there are functions for #total_bytes #free_bytes and the like on memory? See the documentation https://www.rubydoc.info/gems/vmstat/2.3.1/Vmstat/Memory