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

Hi Tao Liu, One more comment, the mod_syment_hash also should be printed by help -s, like symname_hash. crash> set debug 1 debug: 1 crash> help -s ... val_hash_iterations: 530 (avg: 75.7) symname_hash[512]: ff7808 [ 0]: 57 [ 1]: 121 [ 2]: 28 [ 3]: 79 [ 4]: 165 [ 5]: 51 [ 6]: 57 [ 7]: 99 [ 8]: 61 [ 9]: 98 [ 10]: 108 [ 11]: 68

The other patches (2 to 6) look good to me.

Thanks, Kazu -----Original Message----- > 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