[Gluster-devel] Huge memory consumption with quota-marker

Krishnan Parthasarathi kparthas at redhat.com
Thu Jul 2 05:10:30 UTC 2015

----- Original Message -----
> On Wednesday 01 July 2015 08:41 AM, Vijaikumar M wrote:
> > Hi,
> >
> > The new marker xlator uses syncop framework to update quota-size in the
> > background, it uses one synctask per write FOP.
> > If there are 100 parallel writes with all different inodes but on the
> > same directory '/dir', there will be ~100 txn waiting in queue to
> > acquire a lock on on its parent i.e '/dir'.
> > Each of this txn uses a syntack and each synctask allocates stack size
> > of 2M (default size), so total 0f 200M usage. This usage can increase
> > depending on the load.
> >
> > I am think of of using the stacksize for synctask to 256k, will this mem
> > be sufficient as we perform very limited operations within a synctask in
> > marker updation?
> >
> Seems like a good idea to me. Do we need a 256k stacksize or can we live
> with something even smaller?

It was 16K when synctask was introduced. This is a property of syncenv. We could
create a separate syncenv for marker transactions which has smaller stacks.
env->stacksize (and SYNCTASK_DEFAULT_STACKSIZE) was increased to 2MB to support
pump xlator based data migration for replace-brick. For the no. of stack frames
a marker transaction could use at any given time, we could use much lesser, 16K say.
Does that make sense?

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