On Tue, Sep 1, 2020 at 4:22 AM Paul Eggert <eggert@cs.ucla.edu> wrote:
On 9/11/14 1:13 PM, Paul Eggert wrote:
> Thanks, but there's no need for that; just have 'grep' complain if the option
is
> used and O_NOATIME == 0.
On looking into this more today, O_NOATIME seems to be just a best-effort thing
as some GNU/Linux filesystems ignore it, so grep should just join the throng and
not worry whether O_NOATIME actually works.
Also, the O_NOATIME support was withdrawn from fts a couple of years ago, so
'grep -r' can't easily avoid updating atime on directories.
A patch is attached. I'm still of two minds about this. The efficiency argument
for the new option is not as strong as it used to be, now that relatime has
taken over on ext4 style filesystems. So the main argument is "I want to search
through this directory but don't want it to count as an access"; although that's
indeed a use case I'm not quite sure it's worth modifying 'grep' over. It
doesn't seem to be worth using up a scarce option letter over, anyway, so the
attached patch uses just a long option.
I confess to similar ambivalence, but do like the idea. Has anyone run
tests to compare performance on file systems like ext4, btrfs (the
default with Fedora 33) and xfs?