Re: [PATCH RFC] vfs: add a O_NOMTIME flag

[Sage Weil]

On Mon, 11 May 2015, Theodore Ts'o wrote:
> On Sun, May 10, 2015 at 07:13:24PM -0400, Trond Myklebust wrote:
> > That makes it completely non-generic though. By putting this in the
> > VFS, you are giving applications a loaded gun that is pointed straight
> > at the application user's head.
> 
> Let me re-ask the question that I asked last week (and was apparently
> ignored).  Why not trying to use the lazytime feature instead of
> pointing a head straight at the application's --- and system
> administrators' --- heads?

Sorry Ted, I thought I responded already.

The goal is to avoid inode writeout entirely when we can, and 
as I understand it lazytime will still force writeout before the inode 
is dropped from the cache.  In systems like Ceph in particular, the 
IOs can be spread across lots of files, so simply deferring writeout 
doesn't always help.

sage
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