Mailinglist Archive: opensuse (946 mails)

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Re: [opensuse] About relatime and lazytime
On 2017-09-26 21:17, Anton Aylward wrote:
On 26/09/17 02:36 PM, Carlos E. R. wrote:
Hi,

relatively recently, "lazytime" has been added as the default for mounts -
from man mount:


lazytime
Only update times (atime, mtime, ctime) on the
in-memory version of the file inode.

This mount option significantly reduces writes
to the inode table for workloads that perform
frequent random writes to preallocated files.

1. What is 'relatively' in the "relatively recently"?
2. This "added to mounts" is how? As part of the system call?
That would make it part of the kernel.
What version of the kernel are you talking about?

I'm talking of Leap. 42.1 did not have it, 42.2 has it.

The above is extracted directly from the man page, it is not my text.

I don't know if the defaults are applied by the mount command or by systemd.


3. What, in your opinion, is "frequent random writes to preallocated files"?
I ask because in my opinion that means databases, as in updating fields or
rows. while I realise that Thunderbird and Firefox make use of small
SQLite3 databases, how useful is this to those of is who just use those
file
systems for 'regular' stuff like word processing and the regular file
traffic: postfix, OpenOffice, gimp, or updating the myriad of small
configuration dot files in the home directory?

Wait. It is not data writes. It is about writing the timestamp or
updating it each time some data is written to the file (or read).

In traditional unix, each time you read a bit from a file, one timestamp
for that file is changed. Ie, one write operation on directory table per
data read access. Linux inherited this.


4. If a file is closed does that constitute its inode being "evicted from
memory" in this context? or is there some caching done on the principle
that you _might_ want to open it again soon?

I don't know and it is not related to this issue.

--
Cheers / Saludos,

Carlos E. R.
(from 42.2 x86_64 "Malachite" at Telcontar)

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