Re: FFI hashtable?
- From: Coda Highland <chighland@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Sat, 14 Mar 2015 12:08:32 -0700
I've worked on an ARM system with a crypto coprocessor that did CRC
slower in HW than in SW unless you were checksumming huge amounts of
data. It's not often as big of a win as it sounds.
/s/ Adam
On Sat, Mar 14, 2015 at 11:20 AM, Юрий Соколов <funny.falcon@xxxxxxxxx> wrote:
> May be cause not all cpu have such instruction? Not all servers and desktop
> have latest Intel cpu and even later Amd. company i work in has hundreds of
> servers old enough to have no crc32c instruction.
>
> 14.03.2015 16:17 пользователь "Reini Urban" <reini@xxxxxxxxxx> написал:
>>
>> On 03/14/2015 01:27 PM, Юрий Соколов wrote:
>> > https://gist.github.com/funny-falcon/f36851422ab05475d6fd
>> >
>> > It is evolution of khash design.
>>
>> Nice.
>>
>> But why is still nobody using the faster and better iSCSI CRC32-C hash
>> function which is builtin into hardware on modern intel processors for a
>> decade or now also armv7. You cannot beat 5 cycles and the much better
>> characteristics of CRC32-C vs. fnv, murmur or city.
>>
>> Implementation e.g. at
>> https://github.com/rurban/smhasher/blob/master/crc32_hw.c
>>
>> It is also in some zlib libs, which is better for larger keys
>> (threaded). Not on macports though.
>> You really need to probe for a zlib with HW CRC support.
>>
>>
>
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