Date: Tue, 20 May 2003 11:08:07 +0200 (CEST) From: Heiko Schaefer <hschaefer@fto.de> To: current@FreeBSD.org Subject: gbde performance question Message-ID: <20030520105030.U60060@daneel.foundation.hs>
next in thread | raw e-mail | index | archive | help
Hey all, especially Poul,
putting my hardware troubles (still working on those, i am planning to buy
intel-based, non-el-cheapo hardware tomorrow, if i can get any more
flipped bits unti then. i've exhausted all possible causes that i care to
check, by now) aside for a minute, i wanted to ask about the performance i
see.
to be blunt, i wonder what is taking gbde so long to do its thing :)
less bluntly, i'm looking for input if i am interpreting the numbers i see
correctly, and if they make sense to someone who knows the code.
my hardware (again) is a amd athlon xp+ 1800, i got 512mb of ddr ram.
what i do is that i copy data between two local gbde encrypted disks (two
separate, rather modern - udma 66/100 - disks, on two different
controllers).
iostat 1 says something like that:
tty ad0 ad1 ad2 cpu
tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id
0 153 60.57 139 8.25 0.00 0 0.00 31.37 285 8.73 0 0 89 2 9
0 152 60.52 136 8.06 0.00 0 0.00 31.39 284 8.72 0 0 91 0 9
0 153 60.28 144 8.45 0.00 0 0.00 31.15 294 8.95 0 0 92 2 6
0 153 58.17 143 8.11 0.00 0 0.00 31.35 282 8.62 0 0 88 2 9
i get roughtly 9 MB/s throughput on each disk (one disk writing, one
reading) - and most of the time iostat (just like top) says that my cpu is
more or less saturated.
in "ps auwx" i see
USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND
root 509 37.9 0.0 0 12 ?? DL 9:53AM 22:24.24 (g_bde ad2s1e.bde)
root 513 34.3 0.0 0 12 ?? DL 9:53AM 11:49.08 (g_bde ad0s1e.bde)
i figure this is the amount of cpu time that is used by raw number
crunching (and for example does not include disk-io or anything of that
sort). that would mean that ~1/3 of my cpu can do ~8 MB/s of gbde's
crypto. if so, i could estimate that gbde can theoretically process
roughly 25MB/s on this athlon 1800+.
that looks like an rather low number to me. sites such as
http://www.tcs.hut.fi/~helger/aes/rijndael.html
suggest that on a cpu of that speed, memory bandwidth should be the
limiting factor when using AES/Rijndael.
am i overlooking something ?!
thanks for any insight you can provide on the matter, regards,
Heiko
--
Free Software. Why put up with inferior code and antisocial corporations?
http://www.gnu.org/philosophy/why-free.html
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20030520105030.U60060>