[Nottingham] named pipes (fifo) help please

Robert Hart enxrah at nottingham.ac.uk
Wed Oct 26 17:30:06 BST 2005


On Wed, 2005-10-26 at 17:14 +0100, Martin wrote:
> Is the "mv" still atomic even though the old file is getting deleted? 
> (No partial writes noticed despite the coincident read-writes.)

Yes, the file name will only ever point to one inode at once. "cat" will
use whatever inode was in place at the point it opened the file.

> Will this all be cached in RAM by the kernel or will my HDD get 
> thrashed?? (Seems to work ok and the HDD gets hit only occasionally, so 
> the changes must be getting cached.)

It depends slightly on what filesystem and mount options you have, but
generally the cache will do the right thing. However, this will stop
your disk drive from spinning down, and it may discourage the kernel
from doing other things it might do when idle, like readahead.

If you were worried you could mount a ramdisk 

-- 
Robert Hart <enxrah at nottingham.ac.uk>
University of Nottingham


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