Messages in this thread | | | Date | Mon, 24 May 2004 12:43:32 +0200 | From | Jakob Oestergaard <> | Subject | Re: Help understanding slow down |
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On Mon, May 24, 2004 at 05:59:36PM +1000, Nick Piggin wrote: > Phy Prabab wrote: > >NO HT, disabled in bios and did not enable in kernel: > >cat /proc/cpuinfo|grep processor|wc -l > > 2 > >grep SMT .config (2.6.7-rc1) > ># CONFIG_SCHED_SMT is not set > > > >On 2.4.21 I also include "append=noht" > > > > OK good, that makes things simpler. > > I'm out of ideas though. The kernel just doesn't seem to be > the problem here. Can you put together a testcase that causes > the problem and that we can download and reproduce it?
You could try running your program with 'strace -T' to see which system calls are causing the slowdown.
If you make a lot of system calls, this can be a little tedious to go thru though... But it should reveal to you where your program is waiting.
Note; if you use gprof and compile with the '-pg' switch, the profiler will show you a profile of CPU time, not wall-clock time. Your performance problem is wall-clock time, and if your program actually spends a lot of time waiting in some system call, this will *NOT* show up in a normal gprof profile.
/ jakob
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