Messages in this thread | | | Date | Fri, 11 Nov 2005 18:48:16 -0500 | From | Gautam Thaker <> | Subject | 2.6.14-rt9 nanosleep() behavior.. |
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I have noticed that nanosleep() on 2.6.14-rt9 built with real-time options listed at bottom of this page has unexpected behavior. In 2.6.13-RC4-RT53 if one called
nanosleep(20msec)
than actual sleep durations were very close to 20msec. (average number over 1 million samples yielded 20.008msec with minimum of 20.007msec and maximum of 20.060 msec). (2.6.13-RC4-RT53 nanosleep(20msec) histogram can be viewed at:
http://www.atl.external.lmco.com/projects/QoS/compare/j_data/linux/2.6.13-RC4-RT-53-07/basement_prio_95_noload_with_chrt_on_pid_8_to_p97_20msec.out.png
with 2.6.14-rt9, nanosleep(20msec) returns average sleep interval of 21 msec.
Is the previously seen behavior in 2.6.13-RC4-RT-53-07 possible now under latest kernels?
New kernel (2.6.14-rt9) was built with:
Subarchitecture Type (PC-compatible) ---> Processor family (Pentium-Pro) ---> [*] Generic x86 support [*] HPET Timer Support [ ] Ktimers 64bit scalar representation [*] High Resolution Timer Support (1000) High Resolution Timer resolution (nanoseconds) [ ] Symmetric multi-processing support Preemption Mode (Complete Preemption (Real-Time)) ---> --- Thread Softirqs --- Thread Hardirqs --- Preemptible RCU [*] /proc stats for preemptible RCU read-side critical sections [ ] /proc torture tests for RCU [ ] Local APIC support on uniprocessors [*] Machine Check Exception < > Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium <M> Toshiba Laptop support <M> Dell laptop support [ ] Enable X86 board specific fixups for reboot <M> /dev/cpu/microcode - Intel IA32 CPU microcode support <M> /dev/cpu/*/msr - Model-specific register support <M> /dev/cpu/*/cpuid - CPU information support Firmware Drivers ---> High Memory Support (4GB) ---> Memory model (Flat Memory) ---> [*] Allocate 3rd-level pagetables from highmem [ ] Math emulation [*] MTRR (Memory Type Range Register) support [ ] Boot from EFI support (EXPERIMENTAL) [*] Use register arguments (EXPERIMENTAL) [*] Enable seccomp to safely compute untrusted bytecode Timer frequency (1000 HZ) ---> [ ] kexec system call (EXPERIMENTAL)
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