Re: [rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash

2011-01-20 Thread Alexander Leidinger
Quoting Gleb Kurtsou (from Fri, 24 Dec 2010 00:46:20 +0200): Hi, I've recently noticed that hash table use in nullfs was inefficient, 1/3 to half of buckets remained unused. I've started investigating it further and came across SuperFastHash hashing function, SFH (SuperFastHash) has BSD lice

Re: [rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash

2010-12-26 Thread Gleb Kurtsou
On (26/12/2010 15:20), Ivan Voras wrote: > On 26 December 2010 14:24, Gleb Kurtsou wrote: > > On (25/12/2010 20:29), Ivan Voras wrote: > >> On 23.12.2010 23:46, Gleb Kurtsou wrote: > >> > >> > For testing I've used dbench with 16 processes on 1 Gb swap back md > >> > device, UFS + SoftUpdates: > >

Re: [rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash

2010-12-26 Thread Ivan Voras
On 26 December 2010 14:24, Gleb Kurtsou wrote: > On (25/12/2010 20:29), Ivan Voras wrote: >> On 23.12.2010 23:46, Gleb Kurtsou wrote: >> >> > For testing I've used dbench with 16 processes on 1 Gb swap back md >> > device, UFS + SoftUpdates: >> > Old hash (Mb/s): 599.94  600.096 599.536 >> > SFH h

Re: [rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash

2010-12-26 Thread Gleb Kurtsou
On (25/12/2010 20:29), Ivan Voras wrote: > On 23.12.2010 23:46, Gleb Kurtsou wrote: > > > For testing I've used dbench with 16 processes on 1 Gb swap back md > > device, UFS + SoftUpdates: > > Old hash (Mb/s): 599.94 600.096 599.536 > > SFH hash (Mb/s): 612.439 612.341 609.673 > > > > It's just

Re: [rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash

2010-12-25 Thread Ivan Voras
On 23.12.2010 23:46, Gleb Kurtsou wrote: > For testing I've used dbench with 16 processes on 1 Gb swap back md > device, UFS + SoftUpdates: > Old hash (Mb/s): 599.94 600.096 599.536 > SFH hash (Mb/s): 612.439 612.341 609.673 > > It's just ~1% improvement, but dbench is not a VFS metadata intensi

Re: [rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash

2010-12-24 Thread Gleb Kurtsou
On (24/12/2010 00:46), Gleb Kurtsou wrote: > Hi, > > I've recently noticed that hash table use in nullfs was inefficient, 1/3 > to half of buckets remained unused. I've started investigating it Nullfs patch I've forgotten to attach before. It adds vfs.nullfs.buckets tunable to change number of ha

[rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash

2010-12-23 Thread Gleb Kurtsou
Hi, I've recently noticed that hash table use in nullfs was inefficient, 1/3 to half of buckets remained unused. I've started investigating it further and came across SuperFastHash hashing function, SFH (SuperFastHash) has BSD license, used in WebKit and other open source projects. Detailed descri