Re: 2.1.111 VM and low memory machines

Chris Wedgwood (
Mon, 27 Jul 1998 18:06:30 +1200

On Mon, Jul 27, 1998 at 01:41:00AM -0400, Albert D. Cahalan wrote:

> Except for some broken old Ethernet cards, your data seems to
> indicate that the default NFS block size should vary with the
> total amount of memory.

Nah, I think it should default to 8k. For those with low memory (i.e. below
16MB) I think its reasonable that they have to change their mounts arguments
to make things more sane.

> There is a TCP/IP window size CONFIG_* option that might deserve
> similar treatment.

No there isn't. If you mean CONFIG_SKB_LARGE (which, I think, used to allow
large TCP windows), it not used anywhere in the kernel source and should be
removed from the file(s). I've submitted patches in the past that
included removing this.

If you want large windows in 2.1.x, then try to convince DaveM and whomever
else has a say in this that it doesn't break stuff. I have sysctl patches
that allow up to 64k windows (without scaling) which I find work great over
satellite, but I'm told windows over 32k break buggy stacks.

Arguably, TCP stacks should use wscale, but not that many stacks seem to
support this (basically, only Linux 2.1.x and windows 95+/98, not NT, not

I have to say, I've never seen it break anything, but I've not looked all
that hard either. I'm also of the opinion, if it breaks some obscure stacks
then too bad. Negotiated tcp options (timestamps, wscale, SACK, etc) break
Ultrix - but do we disable them by default?


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