Ben,
Here is an attempt.
c -> Is the total cache size (MRU + MFU)
p -> represents the limit of MRU
(c - p) -> represents the limit of MFU
c_max, c_min -> hard limits
size -> Total amount consumed by ARC
memory_throttle_count -> The number of times ZFS decided to
throttle ARC growth.
ARC maintains ghost lists for MRU and MFU. When it decides to
evict a buffer from the MRU/MFU, the data buffer is freed. However,
it moves the corresponding header into these ghost lists.
In future, when we have a hit on one of these ghost lists it
is a indication to the algorithm that the corresponding (MRU/MFU)
should have been larger to accomodate it.
mfu_ghost_hits -> These are the hits into the Ghost list
mru_ghost_hits
This is used to correct the size of MRU/MFU by adjusting the value
of 'p' (arc.c:arc_adjust()).
I know this is not complete.
Thanks and regrads,
Sanjeev.
On Wed, Aug 20, 2008 at 04:04:59AM -0700, Ben Rockwood wrote:
> Would someone "in the know" be willing to write up (preferably blog)
> definitive definitions/explanations of all the arcstats provided via kstat?
> I'm struggling with proper interpretation of certain values, namely "p",
> "memory_throttle_count", and the mru/mfu+ghost hit vs demand/prefetch hit
> counters. I think I've got it figured out, but I'd really like expert
> clarification before I start tweaking.
>
> Thanks.
>
> benr.
>
>
> This message posted from opensolaris.org
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