Messages in this thread |  | | Date | Tue, 20 Feb 2007 13:02:26 -0800 | From | Stephen Hemminger <> | Subject | Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz? |
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On Tue, 20 Feb 2007 21:45:05 +0100 bert hubert <bert.hubert@netherlabs.nl> wrote:
> On Tue, Feb 20, 2007 at 02:40:40PM -0500, Benjamin LaHaise wrote: > > > Make sure your system is idle. Userspace bloat means that *lots* of idle > > activity occurs in between timer ticks on recent distributions -- all those > > You hit the nail on the head. I had previously measured with X shut down, > but the effect didn't disappear. > > With init=/bin/bash, recvfrom suddenly takes from 900nsec to 1.3usec, with > only slight correlation between inter-call delay and cycles spent. > > I'm investigating this further as it appears this has a real life effect on > my P4 - a drastic one! > > processor : 0 > vendor_id : GenuineIntel > cpu family : 15 > model : 4 > model name : Intel(R) Pentium(R) 4 CPU 3.00GHz > stepping : 1 > cpu MHz : 3000.131 > cache size : 1024 KB > fdiv_bug : no > hlt_bug : no > f00f_bug : no > coma_bug : no > fpu : yes > fpu_exception : yes > cpuid level : 5 > wp : yes > flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca > cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx > constant_tsc pni monitor ds_cpl cid xtpr > bogomips : 6003.91 > clflush size : 64 > > Thanks for your help! >
What happens with preempt if your process is high priority or SCHED_FIFO/SCHED_RR?
-- Stephen Hemminger <shemminger@linux-foundation.org> - 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/
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