On Wed, Aug 29, 2007 at 01:15:45AM -0700, Martin Knoblauch wrote:
quoted text >
> --- Fengguang Wu <wfg@mail.ustc.edu.cn> wrote:
>
> > You are apparently running into the sluggish kupdate-style writeback
> > problem with large files: huge amount of dirty pages are getting
> > accumulated and flushed to the disk all at once when dirty background
> > ratio is reached. The current -mm tree has some fixes for it, and
> > there are some more in my tree. Martin, I'll send you the patch if
> > you'd like to try it out.
> >
> Hi Fengguang,
>
> Yeah, that pretty much describes the situation we end up. Although
> "sluggish" is much to friendly if we hit the situation :-)
>
> Yes, I am very interested to check out your patch. I saw your
> postings on LKML already and was already curious. Any chance you have
> something agains 2.6.22-stable? I have reasons not to move to -23 or
> -mm.
Well, they are a dozen patches from various sources. I managed to
back-port them. It compiles and runs, however I cannot guarantee
more...
quoted text > > > Another thing I saw during my tests is that when writing to NFS,
> > the
> > > "dirty" or "nr_dirty" numbers are always 0. Is this a conceptual
> > thing,
> > > or a bug?
> >
> > What are the nr_unstable numbers?
> >
>
> Ahh. Yes, they go up to 80-90k pages. Comparable to the nr_dirty
> numbers for the disk case. Good to know.
>
> For NFS, the nr_writeback numbers seem surprisingly high. They also go
> to 80-90k (pages ?). In the disk case they rarely go over 12k.
Maybe the difference of throttling one single 'cp' and a dozen 'nfsd'?
Fengguang
