On Mon, 03.01.11 09:54, Chris Adams (cmadams@hiwaay.net) wrote:
Once upon a time, Adam Jackson ajax@redhat.com said:
Sadly this turns out not to be the case, at least if I'm reading fs/pipe.c correctly. O_NOATIME will turn off atime updates, but mtime and ctime are still modified on every pipe write, and there's no such thing as O_NOCMTIME even though the filesystem layer does have the concept internally. Which means device-backed filesystems will see write traffic just for using named pipes.
Heck of lame. Someone should fix that.
The behavior follows the standard, so it shouldn't just be changed by default without checking if anybody uses the standard behavior.
Well, I think introducing O_NOCTIME the same way O_NOATIME was introduced would be unproblematic: only if it is set the normal ctime behaviour would be disabled.
But yeah, I agree with ajax, the fact that the ctime of a fifo is updated all the time and there is no way around it is kinda ridiculous... And it gives the jack folks a really good reason not to stick a fifo into /tmp.
Lennart