Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers
Jeff Layton <[email protected]>
| Newsgroups | gmane.comp.file-systems.btrfs,gmane.linux.file-systems,gmane.linux.kernel,gmane.linux.kernel.mm,gmane.linux.ports.ppc64.devel,gmane.linux.drivers.platform.x86.devel,gmane.linux.drivers.rdma,gmane.linux.serial,gmane.linux.usb.general,gmane.linux.kernel.autofs,gmane.comp.file-systems.ceph.devel,gmane.comp.file-systems.coda.general,gmane.linux.kernel.efi,gmane.comp.file-systems.ext4,gmane.linux.file-systems.f2fs,gmane.linux.uml.devel,gmane.linux.drivers.mtd,gmane.linux.nfs,gmane.comp.file-systems.nilfs.user,gmane.linux.file-systems.ntfs.devel,gmane.linux.hardware.karma.devel,gmane.linux.file-systems.union,gmane.comp.file-systems.reiserfs.general,gmane.linux.kernel.cifs,gmane.network.samba.internals,gmane.linux.kernel.bpf,gmane.linux.network,gmane.comp.security.apparmor,gmane.linux.kernel.lsm |
|---|---|
| Message-ID | <[email protected]> |
On Thu, 2023-09-28 at 11:48 -0400, Arnd Bergmann wrote: > On Thu, Sep 28, 2023, at 07:05, Jeff Layton wrote: > > This shaves 8 bytes off struct inode, according to pahole. > > > > Signed-off-by: Jeff Layton <[email protected]> > > FWIW, this is similar to the approach that Deepa suggested > back in 2016: > > https://lore.kernel.org/lkml/[email protected]/ > > It was NaKed at the time because of the added complexity, > though it would have been much easier to do it then, > as we had to touch all the timespec references anyway. > > The approach still seems ok to me, but I'm not sure it's worth > doing it now if we didn't do it then. > I remember seeing those patches go by. I don't remember that change being NaK'ed, but I wasn't paying close attention at the time Looking at it objectively now, I think it's worth it to recover 8 bytes per inode and open a 4 byte hole that Amir can use to grow the i_fsnotify_mask. We might even able to shave off another 12 bytes eventually if we can move to a single 64-bit word per timestamp. It is a lot of churn though. -- Jeff Layton <[email protected]>