Messages in this thread | | | Date | Mon, 17 Jun 2002 13:31:15 -0700 (PDT) | From | dean gaudet <> | Subject | Re: 3x slower file reading oddity |
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On Mon, 17 Jun 2002, Benjamin LaHaise wrote:
> On Mon, Jun 17, 2002 at 01:03:15PM -0700, dean gaudet wrote: > > 3x slower with the two cats in parallel. > > cat uses an incredibly small buffer for file io (4KB on x86), so > running multiple cats in parallel will simply thrash your disk. > What you really want is to run the open()s in parallel and the > read()s sequentially (or in parallel with a large buffer to cut > down on the seek cost).
using a 64KB buffer makes the xargs -P2 only twice as long as the -P1 ... so that's an improvement, but still something seems odd. (btw, many of the files are tiny anyhow -- a bunch of maildirs mixed in amongst the files.)
i'll try playing around with threading the open()s.
-dean
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