On 2015-12-31 13:50, Allan Jude wrote: > On 2015-12-31 13:32, Jonathan T. Looney wrote: >> On 12/31/15, 2:15 AM, "Allan Jude" <allanj...@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. >
I found the cause of my bogus benchmark, the world on my test machine was just old enough to be missing jmg@'s bufsize patch. Now the difference is about 1 second on a 2GB file, so ignore my foolishness. -- Allan Jude
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