Re: NFS client latencies

Trond Myklebust
2005-03-31T14:32:32Z

to den 31.03.2005 Klokka 15:58 (+0200) skreiv Ingo Molnar:
> * Trond Myklebust <trond.myklebust@fys.uio.no> wrote:
>
> > > + int res;
> > ^^^^^^^ Should be "int res = 0;"
>
> your patch works fine here - but there are still latencies in
> nfs_scan_commit()/nfs_scan_list(): see the attached 3.7 msec latency
> trace. It happened during a simple big-file writeout and is easily
> reproducible. Could the nfsi->commit list searching be replaced with a
> radix based approach too?

That would be 100% pure overhead. The nfsi->commit list does not need to
be sorted and with these patches applied, it no longer is. In fact one
of the cleanups I still need to do is to get rid of those redundant
checks on wb->index (start is now always set to 0, and end is always
~0UL).

So the overhead you are currently seeing should just be that of
iterating through the list, locking said requests and adding them to our
private list.

Cheers,
Trond

--
Trond Myklebust <trond.myklebust@fys.uio.no>