Linux and L2 Cache; Sempron vs. Athlon
by Kristopher Kubicki on August 18, 2004 2:29 AM EST- Posted in
- Linux
As AMD rolls out its newest Sempron processor line, many readers are asking us if the reduced cache Socket 754 Sempron 3100+ really compares with already shipping Athlon 64 single channel solutions. Today we take two single channel, 1.8GHz processors with differing L2 cache and compare them in the same Linux benchmarks we have used in the past. The Athlon 64 2800+ and the Sempron 3100+ are nearly identical processors, except for the 256KB cache difference. There is also a $20 delta between the two retail products, so today we decide if the $20 difference between the two processors is worth the sacrafice of level two cache and 64-bit addressing. We have provided benchmarks of another 1.8GHz 32-bit processor from AMD, as well as the Athlon 64 3000+ for reference only.
Update: This article got pushed live prematurely. If you read it before 12PM EST on the 18th, you read an incomplete, unfinished article.
| Performance Test Configuration | |
| Processor(s): | AMD Athlon 64 2800+ (130nm,
1.8GHz, 512KB L2 Cache) |
| RAM: | 2 x 512MB PC-3200 CL2 (400MHz) |
| Memory Timings: | Default |
| Motherboard: | Chaintech ZNF-250 (nForce3,
Socket 754) DFI NFII Infinity (nForce2, Socket 462) |
| Operating System(s): | SuSE 9.1 Professional (32 bit) Linux 2.6.4-52-default |
| Compiler: | linux:~ # gcc -v Reading specs from /usr/lib/gcc-lib/i586-suse-linux/3.3.3/specs Configured with: ../configure --enable-threads=posix --prefix=/usr --with-local-prefix=/usr/local --infodir=/usr/share/info --mandir=/usr/share/man --enable-languages=c,c++,f77,objc,java,ada --disable-checking --libdir=/usr/lib --enable-libgcj --with-gxx-include-dir=/usr/include/g++ --with-slibdir=/lib --with-system-zlib --enable-shared --enable-__cxa_atexit i586-suse-linux Thread model: posix gcc version 3.3.3 (SuSE Linux) |
| Libraries: | linux:~ # /lib/libc.so.6
GNU C Library stable release version 2.3.3 (20040405), by Roland McGrath et al.
Copyright (C) 2004 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Configured for i686-suse-linux.
Compiled by GNU CC version 3.3.3 (SuSE Linux).
Compiled on a Linux 2.6.4 system on 2004-04-05.
Available extensions:
GNU libio by Per Bothner
crypt add-on version 2.1 by Michael Glad and others
linuxthreads-0.10 by Xavier Leroy
GNU Libidn by Simon Josefsson
NoVersion patch for broken glibc 2.0 binaries
BIND-8.2.3-T5B
libthread_db work sponsored by Alpha Processor Inc
NIS(YP)/NIS+ NSS modules 0.19 by Thorsten Kukuk
Thread-local storage support included.
Report bugs using the `glibcbug' script to |
Even though we are using 1GB of memory in a dual channel configuration, the Socket 754 platform will only perform in single channel mode. Fortunately for AMD, since the memory controller is directly on the processor we do not see large latencies going from dual channel to single channel mode. Only the Athlon 64 2800+ can run 64-bit binaries, so for the sake of experiment we will only look at 32-bit binaries today. We have looked at 32-bit versus 64-bit performance in the past, and we will revisit it again in a few weeks, so today we will just focus on 32-bit performance.
Also keep in mind the GCC 3.3.3 included with SuSE 9.1 Pro has many back ported options from the official 3.4.1 tree. Our results with GCC 3.3.3 are much more optimized than the standard GCC 3.3.3.
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KristopherKubicki - Saturday, August 21, 2004 - link
Aces options actually degrade performance on our test machine.Kristopher
KristopherKubicki - Saturday, August 21, 2004 - link
I am not making these up... really.Xeon 3.6GHz EM64T, 1GB DDR2-400, TSCP 1.8.1
=================================================================
linux:~/work/tscp181 # /opt/gcc-mainline/bin/gcc -v
Reading specs from /opt/gcc-mainline/lib64/gcc/x86_64-suse-linux/3.4.1/specs
Configured with: ../configure --enable-threads=posix --prefix=/opt/gcc-mainline --with-local-prefix=/usr/local --infodir=/opt/gcc-mainline/share/info --mandir=/opt/gcc-mainline/share/man --libdir=/opt/gcc-mainline/lib64 --libexecdir=/opt/gcc-mainline/lib64 --enable-languages=c,c++,f77,objc,java,ada --enable-checking --enable-libgcj --with-gxx-include-dir=/opt/gcc-mainline/include/g++ --with-slibdir=/lib64 --with-system-zlib --enable-shared --enable-__cxa_atexit x86_64-suse-linux
Thread model: posix
gcc version 3.4.1 20040508 (prerelease) (SuSE Linux)
=================================================================
-O3 -funroll-loops -frerun-cse-after-loop -march=nocona
Nodes per second: 388145 (Score: 1.596)
-O2 -funroll-loops -frerun-cse-after-loop -march=nocona
Nodes per second: 365722 (Score: 1.504)
-O3 -funroll-loops -frerun-cse-after-loop
Nodes per second: 378021 (Score: 1.555)
-O2 -funroll-loops -frerun-cse-after-loop
Nodes per second: 365722 (Score: 1.504)
-O3 -march=nocona -funroll-loops -fomit-frame-pointer -ffast-math -fprofile-arcs
Nodes per second: 311526 (Score: 1.281)
-O2 -march=nocona -funroll-loops -fomit-frame-pointer -ffast-math -fprofile-arcs
Nodes per second: 299173 (Score: 1.230)
-O2 -funroll-loops -fomit-frame-pointer -ffast-math -fprofile-arcs
Nodes per second: 279724 (Score: 1.150)
-O3 -funroll-loops -fomit-frame-pointer -ffast-math -fprofile-arcs
Nodes per second: 299173 (Score: 1.230)
Matthew Daws - Saturday, August 21, 2004 - link
Not true. These options are on at least GCC 3.2.2, and on the P4 system I have access to (it's a university computer) I get 422K nodes/sec using the above compiler settings from Ace's.--Matt
KristopherKubicki - Saturday, August 21, 2004 - link
Matthew Daws: Again, he is using GCC 3.4.1 which has huge optimizations and is something we havent moved over to yet.Kristopher
ThePlagiarmaster - Saturday, August 21, 2004 - link
Oops, forgot, MS says 1st half 2005 now for Win64. So we can expect it in June...ROFL. Still the Semprons will be eaten for lunch then by next xmas by 64bit chips that are only $20 more right now. Then again, AMD could just solve the problem by turning on 64bit for Semprons :)Plag
Matthew Daws - Saturday, August 21, 2004 - link
Kris,Sorry to keep harping on here. But if you look over at Ace's:
http://www.aceshardware.com/forum?read=115094123
You'll find the compiler options you need to get much better results (I'm getting 291K now, on a 2GHz celeron). The general opinion is that TSCP favours the P4 without some careful compiler work. The Athlon numbers, with stock compiler options, are probably OK. But the P4 numbers in the older article seem very low...
--Matt
ThePlagiarmaster - Saturday, August 21, 2004 - link
I'm having a hard time with any recommendation of the sempron over 64bit cpus that are only 10% more (we're talking like $20 here). Nobody will use more than 4gb with these. Thats a given. However, the 64bitness can't be overlooked. Look at the examples AMD has already showed (recently for example). That panorama filter they showed with 57% improvement in speed, and the other thing in the same news post showing 47% improvement. AFAIK neither of these were using more than 4GB. This is with a BETA Win64!http://www.amd.com/us-en/Corporate/VirtualPressRoo...
These are only two examples of TONS that will be on the way shortly (immediately following the OS from MS that is). Intel is now backing this stuff too. Expect more 64bit ports, especially with MS finally getting off the collective ARSES and saying windows64 will be done this year (nah, I say jan/feb...but the point's still valid). This stuff is coming (encryption shows HUGE benefits, and zipping too with nowhere near 4GB), why cut yourself from the game for $20? If $20 is going to break your bank, you have no business buying a PC. Spend it on your kids diapers or shoes instead...LOL
Plag
Matthew Daws - Saturday, August 21, 2004 - link
Kris,I found the following in the source file main.c for TSCP 1.8.1:
/* Score: 1.000 = my Athlon XP 2000+ */
Checking, this means that the author gets circa 243K nodes/sec with his Athlon XP 2000+. I think, in light of this, that my numbers seem correct and yours seem way of base.
Cheers, --Matt
balzi - Saturday, August 21, 2004 - link
Helloooo.. !!!! am I using a mute account??is there any answer to the muddle of benchmark graphs.. please humour me by actually saying something.. Even 'I couldn't be stuffed fixing them' would be good.
thanks
PrinceGaz - Friday, August 20, 2004 - link
40-bit physical address space is 1TB, the 48-bit virtual address space allows for a range of up to 256TB. I think that should be sufficient for the lifetime of the Opteron / Athlon 64.