On 2/24/2021 1:20 PM, Steve French wrote:
Added additional patch to add "acregmax" so now behavior is more similar to nfs.
"acregmax" changes file metadata caching timeout
"acdirmax" changes directory metadata caching
"actimeo" does what it did before - and changes both.
Clever. It's a little weird that specifying either max with
actimeo will kick a warning, and maybe surprising to someone
who sets both maxes to the same value will see actimeo instead.
But they'll get over that. :)
You can add to all three, my
Reviewed-By: Tom Talpey <tom@xxxxxxxxxx>
On Wed, Feb 24, 2021 at 11:31 AM Steve French <smfrench@xxxxxxxxx> wrote:
On Wed, Feb 24, 2021 at 10:11 AM Tom Talpey <tom@xxxxxxxxxx> wrote:
On 2/23/2021 8:03 PM, Steve French wrote:
Updated version incorporates Ronnie's suggestion of leaving the
default (for directory caching) the same as it is today, 1 second, to
avoid
unnecessary risk. Most users can safely improve performance by
mounting with acdirmax to a higher value (e.g. 60 seconds as NFS
defaults to).
nfs and cifs on Linux currently have a mount parameter "actimeo" to control
metadata (attribute) caching but cifs does not have additional mount
parameters to allow distinguishing between caching directory metadata
(e.g. needed to revalidate paths) and that for files.
The behaviors seem to be slightly different with this change.
With NFS, the actimeo option overrides the four min/max options,
and by default the directory ac timers range between 30 and 60.
The CIFS code I see below seems to completely separate actimeo
and acdirmax, and if not set, uses the historic 1 second value.
That's fine, but it's completely different from NFS. Shouldn't we
use a different mount option, to avoid confusing the admin?
Ugh ... You are probably right. I was trying to avoid two problems:
1) (a minor one) adding a second mount option rather than just one (to
solve the same problem). But reducing confusion is worth an extra
mount option
2) how to avoid the user specifying *both* actimeo and acregmax -
which one 'wins' (presumably the last one in the mount line)
We could check for this and warn the user in mount.cifs so maybe not
important to worry about in the kernel though.
I will add the acregmax mount option and change actimeo to mean
if (actimeo is set)
acregmax = acdirmax = actimeo
--
Thanks,
Steve
