| Re: [chrony-dev] What Linux distributions include Chrony? |
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On Mon, Nov 23, 2009 at 12:45:19PM +0100, Miroslav Lichvar wrote:
> > By the way, I noticed in the ntp discussions that claim that ntp can handle
> > about twice as many requests per second as can chrony. Any suspicions as to
> > why?
>
> I'm seeing the opposite here. ntpd seems to stop replying at certain
> packet rate which then uses less CPU, looks like a buffer is
> overflowing somewhere. CPU utilization is the same when the packet
> rate is set so both reply to everything (about 12000 pps).
Here is an oprofile output for chronyd:
samples % image name symbol name
878 12.5071 chronyd read_from_socket
774 11.0256 chronyd get_offset_correction
639 9.1026 chronyd SCH_MainLoop
630 8.9744 [vdso] (tgid:31244 range:0x7fff28bff000-0x7fff28c00000) [vdso] (tgid:31244 range:0x7fff28bff000-0x7fff28c00000)
503 7.1652 chronyd TMX_GetOffsetLeft
464 6.6097 chronyd transmit_packet
373 5.3134 chronyd send_packet
299 4.2593 chronyd NSR_ProcessReceive
254 3.6182 chronyd LCL_ReadCookedTime
235 3.3476 chronyd UTI_AddDoubleToTimeval
I think it looks good. Probably the only thing we can easily improve
is to avoid calling TMX_GetOffsetLeft if there is no slewing currently
running.
--
Miroslav Lichvar
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