Re: [Crash-utility] [PATCH v2] Improve the performance of symbol searching for kernel modules

-----Original Message----- > > (BTW, at a glance I'm not sure why the 2nd stage is needed... > > sp_hashed was already checked with STREQ in symname_hash_search if found, > > otherwise st->synmane_hash should include all kernel symbols..) > > > Hello Kazu, > > Yes, from my view I also think the 2nd stage is not necessary, I have > thought about removing > it as well, but I just don't want to go too far at one step. :-) OK, I see. > > One more, do you have any slow command that will be especially improved > > by the patch? I'm ok with the sym command taking 3ms :-) > > I'd like to know why the patch should be applied or how much the worst > > command etc. will be improved, to see the importance of it. > > > > No, I don't have a specific slow command. Because the modified functions > symbol_search and symbol_exists are fundamental and widely used by > other crash functions, thus the benefit of performance improvement can > get accumulated. In addition, the time consumption for T3 shortened greatly, > from 2.4 to 0.017, maybe this can be one of the reasons. OK. As far as I've checked a large machine (with 192 CPUs), there are not many commands but several commands call symbol_search and symbol_exists returning "not found" many times: symbol_search symbol_exists found NULL found NULL startup 95 21 29 21 ps -m 1951 1951 0 0 irq 1850 0 0 13448 irq -a 1850 0 884 10777 irq -s 1850 0 884 10777 timer 193 193 0 0 Actually, these commands were obviously improved by the patch. So let's add some explanation like this to the commit log:

" 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." Anyway, I'll review the patch, please wait for a while.

Thanks, Kazu -- Crash-utility mailing list Crash-utility(a)redhat.com https://listman.redhat.com/mailman/listinfo/crash-utility