[Stgt-devel] Strange throughput results with tgtd and iSCSI

[FUJITA Tomonori]

On Thu, 7 Feb 2008 13:20:16 -0500
Pete Wyckoff <pw at osc.edu> wrote:

> pw at osc.edu wrote on Thu, 07 Feb 2008 11:57 -0500:
> > bart.vanassche at gmail.com wrote on Thu, 07 Feb 2008 17:04 +0100:
> > > Results on Ethernet:
> > > For a block size of 512 KB: write throughput of 43 MB/s.
> > > For a block size of 1 MB: write throughput of 15 MB/s.
> > 
> > Redoing the tests at 1G keeps it all in RAM for me.  Then I get 95
> > MB/s at 512 kB and 88 MB/s at 1MB, so confirming your performance
> > disparity, but not finding numbers nearly so bad.
> 
> I looked at logs on tgtd.  These are writes.  With my kernel, the 1M
> case just sends two 512k requests back-to-back due to initiator
> block limits.  So there are an identical series of requests in both
> cases.

With the current git tree, it's possible to send a 1MB SCSI request, I
think.