Re: PREEMPT_RT vs I-PIPE: the numbers, part 2

Karim Yaghmour
2005-06-22T20:31:47Z

Ingo Molnar wrote:
> the UDP-over-localhost latency was a softirq processing bug that is
> fixed in current PREEMPT_RT patches. (real over-the-network latency was
> never impacted, that's why it wasnt noticed before.)

That's good to hear, but here are some random stats from the
idle run:

Measurements | Vanilla | preemp_rt | ipipe
---------------+-------------+----------------+-------------
fork | 95us | 157us (+65%) | 97us (+2%)
open/close | 1.4us | 2.1us (+50%) | 1.4us (~)
execve | 355us | 452us (+27%) | 365us (+3%)
select 500fd | 12.7us | 27.7us (+118%) | 12.7us (~)
mmap | 660us | 2886us (+337%) | 673us (+2%)
... | ... | ... | ...

Here's a under ping flood conditions:

Measurements | Vanilla | preemp_rt | ipipe
---------------+-------------+----------------+-------------
fork | 112us | 223us (+99%) | 121us (+8%)
open/close | 1.7us | 3.0us (+76%) | 1.8us (+6%)
execve | 421us | 652us (+55%) | 467us (+11%)
select 500fd | 14.6us | 38.1us (+161%) | 15.5us (+6%)
mmap | 760us | 3936us (+418%) | 819us (+8%)
... | ... | ... | ...

etc. it's like this accross the board.

Unless that fix you mention above takes care of these, there's
something seriously wrong going on here.

Are there existing LMbench results posted of PREEMPT_RT which
one can go back to for comparison?

Karim
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