Currently the sequence for symbol_search to search a symbol is: 1) kernel
symname hash table, 2) iterate all kernel symbols, 3) iterate all kernel
modules and their symbols. In the worst case, if a non-exist symbol been
searched, all 3 stages will be went through. The time consuming status for
each stage is like:
stage 1 stage 2 stage 3
0.007000(ms) 0.593000(ms) 2.421000(ms)
stage 3 takes too much time when comparing to stage 1. This patch introduces
a symname hash table for kernel modules, to improve the performance of symbol
searching.
Functions symbol_search and symbol_exists are fundamental and widely used by
other crash functions, thus the benefit of performance improvement can
get accumulated. For example, "ps -m" and "irq" commands, which call
the functions many times, will become faster with the patch.
v4 -> v5:
1) Seperated kernel modules syment install from kernel syment install,
making them 2 independent functions. Thus kernel modules syment can get sorted
when installed into mod_syment_hash. And spn->cnt stays untouched in v5.
2) Removed syment_is_installed check, it is no longer needed for the new
kernel modules syment install function.
3) Splitted the patches into smaller ones for better patch review.
4) Changed SYMNAME_HASH_INDEX macro into symname_hash_index function.
5) v5 patch can be applied to master branch, for crash-7-branch it needs
slightly modification.
Tao Liu (6):
Implement install and remove operations for mod_symname_hash
Integrate symbol_search with mod_symname_hash search
Extend symname_hash_search with hash table select
Intergrate symbol_exists with mod_symname_hash search
Sync module symbols into mod_symtable whenever module symbols change
Refactor SYMNAME_HASH_INDEX macro to be a function
defs.h | 3 +-
kernel.c | 1 +
symbols.c | 212 ++++++++++++++++++++++++++++++++++--------------------
3 files changed, 137 insertions(+), 79 deletions(-)
--
2.29.2
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