[Discuss] Port Scanning

[daniel at syntheticblue.com (Daniel M Gessel)]

On 2024-08-06 11:47, Dan Ritter wrote:
> Daniel M Gessel wrote:
>> On 2024-08-06 00:31, Bill Bogstad wrote:
>>> We would have a whole lot fewer moles to whack if we changed our tools.
>> In some cases a 5% performance hit is huge - offering up "our programmers
>> make mistakes" as a justification is a non-starter.
> Remember that:
>
> - virtual machines impose a penalty of 1% or more -- worse when
>    not optimally configured
>
> - the mitigations for various speculative execution and memory
>    hammer attacks can impose 2-30% penalties depending on
>    specific programs
>
> - changes between stable kernel versions can be +/- 15% in some
>    cases
>
> All of those can already be cited as  "our programmers make mistakes".
I honestly don't know how the first two address programmer mistakes; can 
you explain?

On the commercial OSs I've worked on, a 5% performance drop would be a 
block-ship issue, depending on where it was seen.