Re: [PATCH] Prevent users from disabling tickless

[Remy Bohmer]

Hi,

2010/12/22 Matthew Wilcox <matthew@xxxxxx>:
>
> Disabling NO_HZ has a serious negative effect on performance -- an extra
> 70us per I/O.  Prevent users from deselecting it.

Enabling NO_HZ has a serious negative effect on realtime due to longer
interrupt handling and less predictability of the system.
We prefer to align the timer interrupt handling to the interrupt
handling of our realtime control loops so they do not bother each
other. A varying moment of the timer interrupt handling would destroy
much realtime responsiveness here.

So, what is good for throughput is usually bad for responsiveness...

This is an example that the many different applications of the Linux
kernel demand a different configuration of the kernel.
I prefer to keep it configurable.

Kind regards,

Remy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/