On 6/5/2009 7:35 AM, Steve Dickson wrote:
Brian R Cowan wrote:
Trond Myklebust<trond.myklebust@xxxxxxxxxx> wrote on 06/04/2009 02:04:58
PM:
Did you try turning off write gathering on the server (i.e. add the
'no_wdelay' export option)? As I said earlier, that forces a delay of
10ms per RPC call, which might explain the FILE_SYNC slowness.
Just tried it, this seems to be a very useful workaround as well. The
FILE_SYNC write calls come back in about the same amount of time as the
write+commit pairs... Speeds up building regardless of the network
filesystem (ClearCase MVFS or straight NFS).
Does anybody had the history as to why 'no_wdelay' is an
export default?
Because "wdelay" is a complete crock?
Adding 10ms to every write RPC only helps if there's a steady
single-file stream arriving at the server. In most other workloads
it only slows things down.
The better solution is to continue tuning the clients to issue
writes in a more sequential and less all-or-nothing fashion.
There are plenty of other less crock-ful things to do in the
server, too.
Tom.
As Brian mentioned later in this thread
it only helps Linux servers, but that's good thing, IMHO. ;-)
So I would have no problem changing the default export
options in nfs-utils, but it would be nice to know why
it was there in the first place...
Neil, Greg??
steved.
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