Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1646352

Re: [v4 1/1] mm: Adaptive hash table scaling

Show all headers | View raw

Hi Andi,

Thank you for looking at this. I mentioned earlier, I would not want to 
impose a cap. However, if you think that for example dcache needs a cap, 
there is already a mechanism for that via high_limit argument, so the 
client can be changed to provide that cap. However, this particular 
patch addresses scaling problem for everyone by making it scale with 
memory at a slower pace.

Thank you,
Pasha

On 05/20/2017 10:07 PM, Andi Kleen wrote:
> Pavel Tatashin <pasha.tatashin@oracle.com> writes:
> 
>> Allow hash tables to scale with memory but at slower pace, when HASH_ADAPT
>> is provided every time memory quadruples the sizes of hash tables will only
>> double instead of quadrupling as well. This algorithm starts working only
>> when memory size reaches a certain point, currently set to 64G.
>>
>> This is example of dentry hash table size, before and after four various
>> memory configurations:
> 
> IMHO the scale is still too aggressive. I find it very unlikely
> that a 1TB machine really needs 256MB of hash table because
> number of used files are unlikely to directly scale with memory.
> 
> Perhaps should just cap it at some large size, e.g. 32M
> 
> -Andi
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
> 

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[v4 0/1] mm: Adaptive hash table scaling Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-05-20 19:10 +0200
  [v4 1/1] mm: Adaptive hash table scaling Pavel Tatashin <pasha.tatashin@oracle.com> - 2017-05-20 19:10 +0200
    Re: [v4 1/1] mm: Adaptive hash table scaling Andi Kleen <andi@firstfloor.org> - 2017-05-21 04:10 +0200
      Re: [v4 1/1] mm: Adaptive hash table scaling Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-05-21 15:00 +0200
        Re: [v4 1/1] mm: Adaptive hash table scaling Andi Kleen <andi@firstfloor.org> - 2017-05-21 18:40 +0200
    Re: [v4 1/1] mm: Adaptive hash table scaling Michael Ellerman <mpe@ellerman.id.au> - 2017-05-22 08:20 +0200
    Re: [v4 1/1] mm: Adaptive hash table scaling Michal Hocko <mhocko@kernel.org> - 2017-05-22 11:30 +0200
      Re: [v4 1/1] mm: Adaptive hash table scaling Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-05-22 15:20 +0200
        Re: [v4 1/1] mm: Adaptive hash table scaling Michal Hocko <mhocko@kernel.org> - 2017-05-22 15:40 +0200
          Re: [v4 1/1] mm: Adaptive hash table scaling Pasha Tatashin <pasha.tatashin@oracle.com> - 2017-05-22 15:50 +0200

csiph-web