On 2020-01-07 11:06, Karel Gardas wrote:
On 1/7/20 7:38 PM, Jordan Geoghegan wrote:
> Using softdep on /tmp is a silly idea. >
Why? To naive eyes it may look like a natural solution: e.g. before
temp file is even created (on drive), it may be deleted which means
there is no meta-data change hence speedup of operation on /tmp. In
case of classical ffs, you will need to create file (sync meta-data
update), save some data (async), delete file (sync meta-data update).
But honestly still need to read the code...
softdep is very complex, and it is by no means perfect or bug free. A
good rule of thumb is to only use softdep on larger partitions that will
see a large number of writes (particularly smaller and/or random writes).
Softdep can chew up a fair amount of kernel memory as well, and in
certain cases changes can take over a minute to actually make their way
on to disk. If softdep was the magic bullet that some people think it
is, it would be enabled by default.
