On Thu, Mar 21, 2013 at 09:51:05PM +0100, Jan Schmidt wrote:
> On 21.03.2013 20:50, Dave Chinner wrote:
> > On Thu, Mar 21, 2013 at 11:59:45AM +0100, Jan Schmidt wrote:
> >> From: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx>
> >> This patch adds execution of a custom command in the middle of all fsstress
> >> operations. Its intended use is the creation of snapshots in the middle of
> >> a
> >> test run.
> > Why do you need fsstress to do this? Why can't you just run fsstress
> > in the background and run a loop creating periodic snapshots in the
> > control script?
> Because I want reproducible results. Same random seed should result in
> the very same snapshots being created.
Why can't you run fsstress for N operations, run a snapshot,
then run it again for M operations? That will give you exactly the
same results, wouldn't it?
> > Also, did you intend that every process creates a snapshot? i.e. it
> > looks lik eif you run a 1000 processes, they'll all run a snapshot
> > operation at X operations? i.e. this will generate nproc * X
> > snapshots in a single run. This doesn't seem very wise to me....
> Agreed, I haven't thought of running more than one process. For the sake
> of reproducibility, I wouldn't want multiple processes for my test case
> I'm not sure if there are other applications than snapshot creation for
> such a feature, so I cannot argue whether to have each process execute
> such a command or not.
If such a feature is necessary, I'd suggest that implementing the
snapshot ioctl as just another operation directly into fsstress is
probably a better way to implement this functionality. That way you
can control the frequency via the command line in exactly the same
way as every other operation....