--As of February 10, 2012 4:24:58 PM +0000, Matthew Seaman is alleged to
have said:
On 10/02/2012 16:04, Matthew Story wrote:
find . -type f -depth 1 -print0 | xargs -n99 -0 -s8192 -c5 rm --
or some such, depending on your needs, I believe in most situations this
particular invocation will also out-perform find ... -delete.
Why would you believe that? find ... -delete calls unlink(2) directly on
each file it finds as it searches the directory tree given that it
matches the other find predicates.
Whereas find ... -print0 | xargs ... rm ... involves a whole complicated
sequence of find doing the same searching and matching job, then
marshalling lists of filenames, piping them between processes, then
xargs exec(2)ing rm with chunks of that arglist; each rm invocation then
finally ... calling unlink(2) on each of the named files.
On the other hand, passing it through xargs makes the deletion
multi-threaded (well, multi-process), while using -delete keeps it all in
one process. Depending on your execution environment, that may be a win.
Actually, I doubt you'ld see much difference above the noise in the
speed of either of those two commands: they're both going to spend the
vast majority of the time waiting for disk IO, and that's common to any
way of doing this job.
This is likely the root of the issue however. ;) (There are probably
some pathological cases of multi-processor, multi-controller, multi-disk
systems where having multiple IO streams would make a difference, but they
are likely to be few for something like this.)
Daniel T. Staal
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