Re: NFS client latencies

[Trond Myklebust <trond.myklebust@fys.uio.no>]

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>

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