[Cluster-devel] [GFS2 PATCH] GFS2: Instruct DLM to avoid queue convert slowdowns

[David Teigland <teigland@redhat.com>]

On Tue, Apr 10, 2012 at 10:12:28AM +0100, Steven Whitehouse wrote:
> Hi,
> 
> On Thu, 2012-04-05 at 12:11 -0400, Bob Peterson wrote:
> > Hi,
> > 
> > Here's another patch (explanation below). This patch replies upon
> > a DLM patch that hasn't fully gone upstream yet, so perhaps it
> > shouldn't be added to the nmw tree until it is. This greatly
> > improves the performance of gfs2_grow in a clustered gfs2 file system.
> > 
> > Regards,
> > 
> I'm still not very keen on dragging in this bit of dlm. If it is really
> needed, then we should use the copy in the dlm itself and not add our
> own copy of it.

The table is equivalent to:
(rq_mode > gr_mode) || (gr_mode == PR && rq_mode == CW)

> When you say that this relies upon this dlm patch, what does that mean?
> What are the consequences of having this patch but not the dlm one? I'm
> wondering whether I should hold off on this at least until the dlm one
> has been finalised and applied.

Yeah, using QUECVT everywhere will make things worse until it's fixed.