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Posted to user@ignite.apache.org by Andrey Mashenkov <an...@gmail.com> on 2017/07/04 12:00:24 UTC
Re: Measuring cache size and performance
Hi,
Looks like:
- "size" is a difference between retention size of cache before and after
test.
- "avgItemSize" is just "size/count"
So, avgItemSize also includes key and value size.
Assume, we have 64-bit JVM with compressed oops, so links has 4 bytes
overhead and there is 8 bytes alignment.
Key size - 8 (long) ~ 24 (as wrapped Long object with aligment).
Value size - 12 (obj header) +8(long) +8(long) + 4(ref to String) + 4(int)
~ 40 (with 8 byte alignment)
Value String field size - 12 (obj header) + 4(hash) + 4(ref to char[]) + ~
24 (with 8 byte alignment)
Char array - 12 (obj header) + 4 (size) + 2*17 (chars) ~ 56 (with 8 byte
alignment)
Total value size: 120 bytes
Total overhead: ~ 147 bytes + (primary index for sql) - (Hashmap buckets
size).
On Fri, Jun 30, 2017 at 9:56 PM, Pascal <pa...@gmail.com> wrote:
> Hi Andrew,
>
> I measured this on 2.0.
> size= 0MB count=64 avgItemSize=7431
> size= 0MB count=128 avgItemSize=3852
> size= 0MB count=256 avgItemSize=2061
> size= 0MB count=512 avgItemSize=1164
> size= 0MB count=1024 avgItemSize=716
> size= 0MB count=2048 avgItemSize=492
> size= 1MB count=4096 avgItemSize=380
> size= 2MB count=8192 avgItemSize=324
> size= 4MB count=16384 avgItemSize=303
> size= 8MB count=32768 avgItemSize=286
> size= 17MB count=65536 avgItemSize=284
> size= 34MB count=131072 avgItemSize=277
> size= 69MB count=262144 avgItemSize=276
> size= 137MB count=524288 avgItemSize=275
> size= 279MB count=1048576 avgItemSize=279
> size= 551MB count=2097152 avgItemSize=275
> size= 1103MB count=4194304 avgItemSize=275
> I assume the amount of unsued free space is negligible with caches bigger
> than +/- 32MB. Correct?
>
> Pascal
>
>
>
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--
Best regards,
Andrey V. Mashenkov