Re: [Crash-utility] [PATCH v5 0/6] Improve kernel modules symbol searching performance

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