Kernel PPS processing

Hal Murray hmurray at
Tue Jul 5 05:55:15 UTC 2016

Stromeko at said:
> On another tangent back to NTP, I'm wondering if it wouldn't make sense to
> offload the timestamp filtering at least to the VC4.  Most NTP boxes would
> run headless anyway, so there'd be 16 processors sitting idle for that sort
> of thing. 

Not likely.  That sort of work doesn't take enough CPU cycles to worry about. 
 If you put it someplace else, it just makes things harder to maintain and 

>> Yeah, I'm wondering why the dealy in Linux kernel for 64 bit A8?
> It wouldn't buy anyone anything of immediate use except having a complete
> additional distro to build and maintain and more memory pressure to deal
> with.  I suspect that eventually a 64bit port will be added anyway to tick a
> checkbox somewhere. 

If you don't need them, 64 bit pointers just take up more memory.  That shows 
up as cache misses.

There are 2 reasons that I know of for needing 64 bit pointers.  The first is 
that you are using more than 32 bits of virtual memory.  The second is that 
your hardware can't address all of physical memory when running in 32 bit 
mode.  If your system uses the top bit for I/O, then you can only use 2 GB of 
physical memory.

These are my opinions.  I hate spam.

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