> Richard; > > I do believe I mention in my original email that the > default sd and ssd xfer is 1 Mbyte. > > The problem, as I said, lies in the fact that maxphys is default 128 > Mbyte which does not make sense especially since the sd/ssd driver > max_xfer_size is 1 Mbyte. (that includes ufs also!)
The limit of size of transfers is, for anything interesting, 1 Mbyte. Perhaps you are making the assumption that maxphys overrides the maximum transfer size dictated by the driver. > In almost all references to maxphys I have come across, almost all have > recommended that maxphys be set to 8388608 bytes as this improves large > transfers without affecting small IO. First, write applications which make such large writes. The largest write by a commercial application (I'm aware of) is 1 Mbyte. > I have a simple observation. > > Solaris is an extremely powerful and scalabel OS but out of the box, the > IO settings is not appropriate for today's fibre attached storages. Even setting the max transfer size to 1 PByte won't make any difference until the applications do such large writes. But even if you set it to 8 Mbytes, the protocol overhead per transfer is so small that the performance gains will be barely noticeable. In other words, AFAICT the current default has solved this particular problem. > If properly tuned however, I do believe that it can outperform most > other general purpose OS. We're trying :-) There is more fertile ground elsewhere. > Solaris 10 attempts to change this by removing many /etc/system > parameters. But for Solaris < 10...... Water under the bridge. -- richard This message posted from opensolaris.org _______________________________________________ perf-discuss mailing list perf-discuss@opensolaris.org
