Re: [PATCH v7 00/11] kallsyms: Optimizes the performance of lookup symbols

[Luis Chamberlain]

On Wed, Oct 26, 2022 at 02:44:36PM +0800, Leizhen (ThunderTown) wrote:
> On 2022/10/26 1:53, Luis Chamberlain wrote:
> > This answers how we don't use a hash table, the question was *should* we
> > use one?
> 
> I'm not the original author, and I can only answer now based on my understanding. Maybe
> the original author didn't think of the hash method, or he has weighed it out.
> 
> Hash is a good solution if only performance is required and memory overhead is not
> considered. Using hash will increase the memory size by up to "4 * kallsyms_num_syms +
> 4 * ARRAY_SIZE(hashtable)" bytes, kallsyms_num_syms is about 1-2 million.
> 
> Because I don't know what hash algorithm will be used, the cost of generating the
> hash value corresponding to the symbol name is unknown now. But I think it's gonna
> be small. But it definitely needs a simpler algorithm, the tool needs to implement
> the same hash algorithm.

For instance, you can look at evaluating if alloc_large_system_hash() would help.

  Luis