http://bugme.osdl.org/show_bug.cgi?id=503
Summary: Hyper Threading technology
Kernel Version: 2.5.65
Status: NEW
Severity: low
Owner: rml@tech9.net
Submitter: koch@dfki.uni-kl.de
Distribution: SuSE 8.0
Hardware Environment: Tyan Thunder i860 S2603, dual XEON 2.8GHz, 512MB RDRAM
Software Environment:
Problem Description: System hung after enabling HT in BIOS
Steps to reproduce: I just installed SuSE 8.0 on the machine, downloaded the
kernel, configured it (i think to sane settings), put it into /boot and ran
lilo. After reboot, i did some benchmarking and the machine seemed to run
fine. When i rebooted a second time and enabled HT in the BIOS, the machine
came up but hung after i logged in (before i could run any benchmark). I
tried everything, but had to use hardware reset. I didn't investigate this
further because the machine had to be finished yesterday.
And now something completely different: Did i say benchmarking? No, not
really. I did compile the 2.5.65 kernel with several different 'make -j'
options to see the impact of HT and if i should enable or disable it and
what the benefit of using a 2.5 kernel would be. I know that compiling a
kernel is not exactly a benchmark, but since the machine will be used in
software development under C i thought it might reveal some issues anyway.
What i found out is interesting (at least for me) and did not meet my (and
other peoples) expectations:
The penalty of using the 2.5.65 kernel (4.6%) is bigger than the penalty of
enabling HT on the 2.4.18 that came with SuSE 8.0 (only 2%). The gain of
using HT on the 2.4.18 is quite astonishing: about 14%.
Here are my numbers:
2 x XEON 2.8GHz (HT enabled) SuSE 8.0 Kernel 2.4.18
real user sys
make - 243.6 229.0 23.6
make -j 2 - 132.9 247.6 26.2
make -j 3 - 120.8 335.3 30.8
make -j 4 - 115.8 406.1 34.6
make -j 5 - 116.0 406.0 34.8
2 x XEON 2.8GHz (HT disabled) SuSE 8.0 Kernel 2.4.18
make - 239.0 223.8 22.3
make -j 2 - 132.3 229.7 23.4
make -j 3 - 132.8 231.3 24.5
2 x XEON 2.8GHz (HT enabled) SuSE 8.0 Kernel 2.5.65
--------- System hung before any benchmark was run ---------
2 x XEON 2.8GHz (HT disabled) SuSE 8.0 Kernel 2.5.65
make - 250.5 229.9 25.0
make -j 2 - 134.9 235.8 27.1
make -j 3 - 136.7 237.3 27.5
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Mon Mar 31 2003 - 22:00:24 EST