> On Mar 8, 2019, at 11:19 AM, Ciprian Dorin Craciun
> <ciprian.crac...@gmail.com> wrote:
>
> I have two small questions about the cache management of `asfd`. (The
> documentation isn't very explicit.)
>
> (In both cases I'm speaking about disk-based cache.)
>
> (A) Using `-dcache 128` with a `-chunksize 10` (i.e. 1MiB) for a
> disk-based cache, would actually allocate 128 MiB from kernel memory
> (i.e. the product of the two)? It is unclear from the documentation.
> (Although I would infer yes, based on the description of memory based
> cache.)
As you've already discovered, the documentation is problematic for the afsd
options.
The -dcache option for a disk-based cache does set the number of dcaches in
memory.
It has a minimum value of 2000 and max of 10000.
(The documentation incorrectly states that 2000 is the max).
However, it does not allocate chunks, but dcache structs, which are 220 bytes
each.
In addition, many of the options interact with each other.
The best guide for how all this _really_ works is the source code - however, the
source itself is quite confusing at times, so I feel your pain.
>
> (B) Using `-files` and `-chunksize` so that their product is larger
> than `-blocks` means that the cache can hold up to as many `-files`
> actual AFS files, but their total size can't be larger than `-blocks`?
> (I.e. if one has a cell with lots of small files, it is OK to
> configure a largish `-chunksize` and `-files` because they will be
> cached up to `-blocks`.)
Correct.
Regards,
--
Mark Vitale
mvit...@sinenomine.net
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