[aur-general] Feedback for rmlint-git and call for a TU

[christopher at ira-kunststoffe.de]

Hello Leonidas,

by using the PKGBUILD directly it should work in all cases.
The problem was really that rmlint was built on a system that has SSE 
4.2
but was shipped to one as binary where it is not available.

The build systems actually used to check the presence of a SSE 4.2 
capable cpu,
but that only works when you build it yourself. The auto detection is 
still there,
but has to be enabled using `--with-sse` explicitly now (not 
recommended for packagers).
It's probably best to remove it alltogether since rmlint also supports 
xxhash which looks a bit more stable.

After all, SSE 4.2 support for rmlint is really very unimportant. Only 
one hash function
has an option to use it (CityHash, not even the default) and I used to 
think "Well, why not pick it up if it's there".
I don't have any metrics myself of how fast the normal variant is 
compared to the SSE variant,
apparently I only own AMD/ARM hardware currently.



Am Mi, 14. Okt, 2015 um 9:29 schrieb Leonidas Spyropoulos 
<artafinde at gmail.com>:
> Hi Christopher,
> 
> On 14/10/15, christopher at ira-kunststoffe.de wrote:
>>  Sorry for the inconvinience, it still crashes with "illegal 
>> instruction".
>>  This is most likely due to the fact that I didn't actually make
>>  --without-sse the default.
>>  Should be (hopefully!) corrected in v2.2.2. I shouldn't push 
>> changes late
>>  night. :)
>> 
> Just tried it on AMD FX 8210 from the package and had the same Illegal
> hardware and code dump. I dowload the PKGBUILD of the package and 
> bumped
> the version to 2.2.2. Compiled and worked.
> 
> Can't you make the code use the hardware SSE 4.2 CRC32C if the 
> hardware
> is there or use a software implementation of it if not?
> 
> What's the difference in performance with and without SSE4.2 enabled -
> can we have some metrics?
> 
> --
> Leonidas Spyropoulos
> 
> Compiled in Vim, sent through mutt.