Hey All!
Recently I realized that I'm unable to fit all my onodes ( 32768
objects/4Mb each/4K alloc unit/no csum) in 15G RAM cache.
Hence decided to estimate Onode in-memory size.
At first I filled 4Mb object with a single 4M write - mempools indicate
~5K mem usage for total onode metadata. Good enough.
Secondly I refill that object with 4K writes. Resulting memusage =
574K!!! Onode itself 704 bytes in 1 object. And 4120 other metadata
items occupies all other space.
Then I removed SharedBlob from mempools. Resulting mem usage = 355K. The
same Onode size. And 3096 other metadata objects. Hence we had 1024
SharedBlob instances thata took ~ 220K.
And finally I removed Blob instances from measurements. Resulting mem
usage = 99K. And 2072 other objects. Hence Blob instances take another ~250K
Yeah, that's the worst case( actually csum enable will give even more
mem use) but shouldn't we revisit some Onode internals due to such numbers?
Thanks,
Igor
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