Adrian Chadd wrote:
> Now, in actual fact, the current swap logs are written to disk
> via the write() method (ie not via an async IO operation) which
> may block anyway. I don't know how this contributes to squid's
> overall performance, but I don't think that call blocks much.
It may, but most often not.
There are two conditions a (small) append write on a active file may
block under:
a) Memory pressure, requiring the write to wait for a new free page when
crossing a page boundary
b) Pagein of filesystem metadata required when allocating a new disk
block.
The first is not very likely to happen unless you are seriously pushing
the disks too hard, or trying to write a lot of data (which is not the
case for swap.state).
Likewise for the second. The pages is almost always paged in already.
Regards
Henrik
Received on Thu Nov 29 2001 - 01:48:48 MST
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