[Stgt-devel] No LUN option in target.c

[FUJITA Tomonori]

On Mon, 26 Nov 2007 13:33:47 +0100
Tomasz Chmielewski <mangoo at wpkg.org> wrote:

> FUJITA Tomonori schrieb:
> > On Mon, 26 Nov 2007 12:25:19 +0100
> > Albert Pauw <albert.pauw at gmail.com> wrote:
> > 
> >> 2007/11/26-12:24:19 | STAT  | 3237 | v1.2.8 | /dev/sdb | Total read 
> >> throughput: 827938.1B/s (0.79MB/s), IOPS 25.3/s.
> >>
> >> The patch didn't make a difference, sorry.
> > 
> > The performances in the configuration don't matter much, but I just
> > run initiator and target on the same machine:
> > 
> > sens:/home/fujita# hdparm -t /dev/sdd
> > 
> > /dev/sdd:
> >  Timing buffered disk reads:   20 MB in  3.15 seconds =   6.35 MB/sec
> 
> (...)
> 
> > sens:/home/fujita# hdparm -t /dev/sdd
> > 
> > /dev/sdd:
> >  Timing buffered disk reads:  410 MB in  3.02 seconds = 135.55 MB/sec
> > 
> > 
> > Seems that haparm isn't an appropriate tool to meature performance but
> > not bad performances.
> 
> It is appropriate, when used appropriately.

Oops, I'm not talking about only cache.

hdparm seems to issue only one outstanding request, the duration is
too short, etc. It's not designed for performance measurement.


> If a block device is used (mounted, swap, md/dm etc.) it is also cached.

Block devices always use page cache (unless you access to it via DIO).


BTW, please let me know if you find that tgt's performance is still
terrible as compared with IET.