Re: computing drop-able caches

[Daniel Walker]

On 02/08/2016 12:57 PM, Khalid Mughal (khalidm) wrote:
> How do we explain the discrepancy between MemAvaiable and MemFree count
> after we drop cache? In following output, which one represents correct
> data?
>
> [Linux_0:/]$ cat /proc/meminfo
> MemTotal:        3977836 kB
> MemFree:          747832 kB
> MemAvailable:    1441736 kB
> Buffers:          123976 kB
> Cached:          1210272 kB
> Active:          2496932 kB
> Inactive:         585364 kB
> Active(anon):    2243932 kB
> Inactive(anon):   142676 kB
> Active(file):     253000 kB
> Inactive(file):   442688 kB
> Dirty:                44 kB
> AnonPages:       1748088 kB
> Mapped:           406512 kB
> Shmem:            638564 kB
> Slab:              65656 kB
> SReclaimable:      30120 kB
> SUnreclaim:        35536 kB
> KernelStack:        5920 kB
> PageTables:        19040 kB
> CommitLimit:     1988916 kB
> Committed_AS:    3765252 kB
>
> [Linux_0:/]$ echo 3 > /proc/sys/vm/drop_caches
> [Linux_0:/]$ cat /proc/meminfo
> MemTotal:        3977836 kB
> MemFree:         1095012 kB
> MemAvailable:    1434148 kB

I suspect MemAvailable takes into account more than just the droppable 
caches. For instance, reclaimable slab is included, but I don't think 
drop_caches drops that part.

Daniel