Mailinglist Archive: opensuse (1256 mails)

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Re: [opensuse] Is 40 dropped packets out of 300,000 high? This is wired cat5 LAN.
On 2017-06-01 14:22, Per Jessen wrote:
Carlos E. R. wrote:

On 2017-06-01 08:31, Per Jessen wrote:

Some more examples -

on machines with uptimes between 30 and 60 days, depending on their
load, I see drop rates of up to 1%. 0.99% on a xen guest, fairly
busy.

On a mirror+squid, uptime 45days, I see 7% drop on one interface.

On four xen guests, not the most potent host machine, each has 10-11%
dropped rx packages ...

two webservers, uptime 1600 days and 92 days, 0 rx drops.

The only possible pattern here might be the xen guests which exhibit
somewhat higher rates than physical machines. My guess is that a
machine dropping packages is simply busy - too much incoming traffic
or too busy to process the interrupts.

Question.

The network "hardware" in the xen guest, is real or emulated?

They're virtual network devices, bridged with the physical device.

Because if it is emulated or virtual, not real hardware, it depends on
the host CPU having time to attend it at the precise instant it is
needed. A real network card will have some internal memory and
processing power, and probably interrupts the machine only when the
data chunk is ready. Perhaps even moves the chunk to main ram via dma,
thus no cpu load.

The physical card still works the way it always has, but there is
obvioulsy more code to be executed to get a network interrupt serviced
in a guest. Something like that.

I have to wonder at how/if the card can write to ram that belongs to the
guest. :-? :-o

--
Cheers / Saludos,

Carlos E. R.
(from 42.2 x86_64 "Malachite" at Telcontar)

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