Re: [PATCH] improve the performance of large sequential write NFS workloads

Trond Myklebust
2010-01-06T18:52:57Z

On Wed, 2010-01-06 at 19:37 +0100, Peter Zijlstra wrote:
> On Wed, 2010-01-06 at 13:26 -0500, Trond Myklebust wrote:
> > OK. It looks as if the only key to finding out how many unstable writes
> > we have is to use global_page_state(NR_UNSTABLE_NFS), so we can't
> > specifically target our own backing-dev.
>
> Would be a simple matter of splitting BDI_UNSTABLE out from
> BDI_RECLAIMABLE, no?
>
> Something like

OK. How about if we also add in a bdi->capabilities flag to tell that we
might have BDI_UNSTABLE? That would allow us to avoid the potentially
expensive extra calls to bdi_stat() and bdi_stat_sum() for the non-nfs
case?

Cheers
Trond