Re: File System Performance Loss in Genera 8.0 (16X slower!)

[cjl@ai.mit.edu (Chris Lindblad)]

    Date: Mon, 9 Jul 90 11:08 EDT
    From: barmar@think.com (Barry Margolin)

    In Genera 8.0, IP is able to reassemble datagrams of arbitrary size.  By
    default it requests 4K bytes of data when reading files from a server on
    the local net (it still defaults to .5K for remote networks, presumably
    because the likelihood of losing a packet is higher).  On an ethernet
    this will be fragmented into at least three packets.

		  Did something different happen in 7.2 (where we never
	had this problem)?  Does anybody have a cure for this?

    Try setting NFS:*LOCAL-NETWORK-TRANSFER-SIZE* back down to 1024.

This is close but not totally correct.

Symbolics NFS uses NFS:*LOCAL-SUBNET-TRANSFER-SIZE* when talking NFS over the
local ethernet (the same internet subnet), NFS:*LOCAL-NETWORK-TRANSFER-SIZE*
when talking through a gateway, but still on the same internet network, and
NFS:*DEFAULT-TRANSFER-SIZE* if the other host is on another internet network.

The defaults for these three variables are:

  NFS:*LOCAL-SUBNET-TRANSFER-SIZE*    8192
  NFS:*LOCAL-NETWORK-TRANSFER-SIZE*   4096
  NFS:*DEFAULT-TRANSFER-SIZE*          512

If you are having problems talking to a sun, and the sun is on the same
ethernet as your Symbolics computer, then first try adjusting
NFS:*LOCAL-SUBNET-TRANSFER-SIZE* to 4096, and see if you get better
throughput.  If that fails, then I suggest adjusting
NFS:*LOCAL-SUBNET-TRANSFER-SIZE* and NFS:*LOCAL-NETWORK-TRANSFER-SIZE* to
1024.