Messages in this thread | | | Date | Wed, 07 Mar 2007 07:52:21 +0100 | From | Eric Dumazet <> | Subject | Re: [patch] epoll use a single inode ... |
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Linus Torvalds a écrit : > > I assume that the *only* reason for having multiple dentries is really > just the output in /proc/<pid>/fd/, right? Or is there any other reason to > have separate dentries for these pseudo-files? > > It's a bit sad to waste that much memory (and time) on something like > that. I bet that the dentry setup is a noticeable part of the whole > sigfd()/timerfd() setup. It's likely also a big part of any memory > footprint if you have lots of them. > > So how about just doing: > - do a single dentry > - make a "struct file_operations" member function that prints out the > name of the thing in /proc/<pid>/fd/, and which *defaults* to just > doing the d_path() on the dentry, but special filesystems like this > could do something else (like print out a fake inode number from the > "file->f_private_data" information) > > There seems to really be no downsides to that approach. No existing > filesystem will even notice (they'll all have NULL in the new f_op > member), and it would allow pipes etc to be sped up and use less memory. >
I would definitly *love* saving dentries for pipes (and sockets too), but how are you going to get the inode ?
pipes()/sockets() can use read()/write()/rw_verify_area() and thus need file->f_path.dentry->d_inode (so each pipe needs a separate dentry)
Are you suggesting adding a new "struct file_operations" member to get the inode ? Or re-intoducing an inode pointer in struct file ?
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