Why is deleting (or reading) files not counted as IO-Wait in top?

From: Matthias Schniedermeyer
Date: Wed Jan 02 2008 - 14:35:26 EST


Hi


Currently i'm deleting about 500.000 files on a XFS-filesystem which
takes a few minutes, as i had a top open i saw that 'wa' is shown as
0.0% (Nothing else running currently) and everything except 'id' is near
the bottom too. Kernel is 2.6.23.11.

So, as 'rm -rf' is essentially a IO (or seek, to be more correct)-bound
task, shouldn't that count as "Waiting for IO"?

The man-page of top says:
'Amount of time the CPU has been waiting for I/O to complete.'

But AFAICT wa only seams to be (ac)counted for writing and not for
reading. I come to that conclusion because, when i fire 'sync' i can see
some percent wa for a few seconds.




Bis denn

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