To clarify some points.

In the 12M lpar, linux saw 8424 KB, the 12M EC saw 68 KB less (8356 kb).
The 68 KB difference was a constant difference in all experiments - this is
probably VM control blocks local to the EC.

The experiment was run in increments of 4M LPAR and EC size. The memory was
manipulated using the mem=xxm parameter of the /etc/zipl.conf file.

EC          Total
size        Linux Memory      used  free  buffers     cached      swap
result
8M          n/a         n/a   n/a   n/a   n/a   n/a   kernel panic
12M         8356        8132  224   620   1760  2852  iplable, slow, no
QETH
16M         12404       12036 368   716   2968  1184  ditto
20M         16452       16104 348   876   5360  68    ditto, reasonable ipl
speed
24M         20500       19908 592   712   2336  2152  OSA, eth0, ssh
available
28M         24548       23844 704   760   3768  656   ditto
32M         28596       28000 596   1144  5236  360   ditto (in LPAR, swap
was 0)

The total is from the "free" command.

Some reasonable conclusions, then, seem to be:

An LPAR or EC takes a minmum of about 4M for "hardware" overhead.
An EC takes 68 KB more that an LPAR
The minimum memory size with QETH/OSA is 24M.
The OSA QETH interface/modules take about 12M.
Use of the swap space at ipl stops about 32M or a bit larger.
The reason Linux uses 4K memory blocks on a zSeries is pretty obvious. That
is the size of the page size on a zSeries.
As to adequate performance vs minimum memory size, YMMV based on your apps
and load.

Regards, Jim
Linux S/390-zSeries Support, SEEL, IBM Silicon Valley Labs
t/l 543-4021, 408-463-4021, [EMAIL PROTECTED]
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