svn commit: r292955 - head/lib/libmd

[Allan Jude]

On 2015-12-31 13:32, Jonathan T. Looney wrote:
> On 12/31/15, 2:15 AM, "Allan Jude" <allanjude at freebsd.org> wrote:
> 
>> It seems these problems also slow things down, a lot:
>>
>> # time md5 /media/md5test/bigdata
>> MD5 (/media/md5test/bigdata) = 6afad0bf5d8318093e943229be05be67
>> 4.310u 3.476s 0:07.79 99.8%     20+167k 0+0io 0pf+0w
>> # time env LD_PRELOAD=/usr/obj/media/svn/md5/head/tmp/lib/libmd.so
>> /usr/obj/media/svn/md5/head/sbin/md5/md5 /media/md5test/bigdata
>> MD5 (/media/md5test/bigdata) = 6afad0bf5d8318093e943229be05be67
>> 4.133u 0.354s 0:04.49 99.7%     20+167k 1+0io 0pf+0w
>>
>> (file is fully cached in ZFS ARC, dd reads it at 11GB/s)
>>
>> Will investigate more tomorrow.
> 
> md5 will be slower than dd due to the extra processing it needs to do to
> generate the hash. I suspect that explains the difference you're seeing
> between those utilities.
> 
> Jonathan
> 
> 
> 

Sorry, you missed my point here.

I replaced MDXFile() with the implementation included in my earlier
email. Using the newer libmd with that code, cut the time to md5 the
SAME data down a lot. I need to do a more scientific test on a box that
isn't doing other stuff still though.

The comment about dd doing 11GB/s, was just to clarify that I wasn't
reading the file from disk, which would introduce other variables.

-- 
Allan Jude

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