Limits on jumbo mbuf cluster allocation

[Rick Macklem]

Garrett Wollman wrote:
> <<On Tue, 12 Mar 2013 23:48:00 -0400 (EDT), Rick Macklem
> <rmacklem at uoguelph.ca> said:
> 
> > I've attached a patch that has assorted changes.
> 
> So I've done some preliminary testing on a slightly modified form of
> this patch, and it appears to have no major issues. However, I'm
> still waiting for my user with 500 VMs to have enough free to be able
> to run some real stress tests for me.
> 
> I was able to get about 2.5 Gbit/s throughput for a single streaming
> client over local 10G interfaces with jumbo frames (through a single
> switch and with LACP on both sides -- how well does lagg(4) interact
> with TSO and checksum offload?) This is a little bit disappointing
> (considering that the filesystem can do 14 Gbit/s locally) but still
> pretty decent for one single-threaded client. This obviously does not
> implicate the DRC changes at all, but does suggest that there is room
> for more performance improvement. (In previous tests last year, I
> was able to get a sustained 8 Gbit/s when using multiple clients.) I
> also found that one of our 10G switches is reordering TCP segments in
> a way that causes poor performance.
> 
If the server for this test isn't doing anything else yet, you could
try a test run with a single nfsd thread and see if that improves
performance.

ken@ emailed yesterday mentioning that out of order reads was resulting
in poor performance related to ZFS and that a single nfsd thread improved
that for his test.

Although a single nfsd thread isn't practical, it suggests that the nfsd
thread affinity code that I had forgotten about and has never been ported
to the new server, might be needed for this. (I'm not sure how to do the
affinity stuff for NFSv4, but it should at least be easy to port the code
so that it works for NFSv3 mounts.)

rick
ps: For a couple of years I had assumed that Isilon would be doing this,
    but they are no longer working on the FreeBSD NFS server, so the
    affinity stuff slipped through the cracks.

> I'll hopefully have some proper testing results later in the week.
> 
> -GAWollman
> _______________________________________________
> freebsd-net at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"