Niagara Configuration
This document keeps track of random niagara configuration options
that you can use to tweak Niagara's behavior.
Command Line Meta-Options
A meta-option is an option which is parsed and handled
by the underlying niagara startup code.
It is not seen by an application.
These options control the configuration of the database, allow
database formatting, etc.
- --format
- Have th estartup code format the underlying shore instance
- --no-main
- Startup the system, but do not run the application niagara_main()
function.
This is used when you just want to use the meta-options and not
perform anything application related
- --format-only
- Combination of --format and --no-main
Environment Variables
- NIAGARA_SM_CONFIG
- Specify the path to the configuration file used to configure
the shore SM instance which Niagara is using.
- NIAGARA_SM_FORMAT
- If set to a positive integer value, indicates that the process
should format the underlying shore store on startup.
This is obsolete; use --format instead.
- NIAGARA_STACKSIZE
- Specify a different stack size for Niagara threads
- IM_LIMIT_INLINE
-
- IM_LIMIT_BACKED
-
- Set the limits for the specified IM adaptive storage format.
A positive number is used directly.
A negative number is interpreted as a power-of-2; for
example -4 -> 2^4 -> 16
Bolo's SimpleCache
I plugged one of my cool hash based caches into Niagara to
see if that would improve the performance of the lexicon.
Each time an item in the lexicon was looked up,
it goes through a shore btree lookup to locate the ID for
the term.
Btree lookups, even in memory, are fairly expensive due to locks
and etc.
So, I tried putting my SimpleCache in to have the Niagara layers
cache the results from the btree lookup and try to avoid the shore
costs.
The end result is that performance wasn't affected terribly.
It improved a bit, but not noticably so compared to the rest
of the system.
It also showed that in-memory btree lookups, even with the lock
crabs and diving through the shore btree code, wasn't as bad
as I originally though.
- IM_LEXICON_CACHE
- [Only applies when Bolo's SimpleCache is plugged in]
If set and >1, create a SimpleCache for each Lexicon with
the specified number of buckets.
If set and ==1, create a SimpleCache with the default number
of buckets.
- IM_LEXICON_CACHE_LIMIT
- Specify the maximum number of entries in the SimpleCache for
each Lexicon.
If not specified the SimpleCache chooses its own default.
Bolo's Home Page
Last Modified:
Thu Dec 5 14:24:15 CST 2002
Bolo (Josef Burger)
<bolo@cs.wisc.edu>