Messages in this thread | | | Date | Mon, 12 Nov 2001 14:14:59 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: File System Performance |
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On Mon, 12 Nov 2001, Lionel Bouton wrote: > > Seems not the case with gnu tar : write isn't even called once on the fd > returned by open("/dev/null",...). In fact a "grep write" on the strace > output is empty in the "tar cf /dev/null" case. Every file in the tar-ed > tree is stat-ed but no-one is read-ed.
Wow. What a sleazy optimization - it can't be anything but a special case.
How do they do it anyway? By matching on the name Or by knowing what the minor/major numbers of /dev/null are supposed to be on that particular operating system?
And what's the _point_ of the optimization? I've never heard of a "tar benchmark"..
Linus
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