From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <9d574933688b2383b1d5edee3deb7236@quanstro.net>
From: erik quanstrom <quanstro@quanstro.net>
Date: Tue, 31 Mar 2009 08:54:40 -0400
To: 9fans@9fans.net
In-Reply-To: <3840643f-ce10-46dc-891a-7a31f6d489c4@l1g2000yqk.googlegroups.com>
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Subject: Re: [9fans] Latest pull killed my server
Topicbox-Message-UUID: ce2b356c-ead4-11e9-9d60-3106f5b1d025

	/* compute log10(ether->mbps) into lg */
	for(lg = 0, mb = ether->mbps; mb >= 10; lg++)
		mb /= 10;
	if (lg > 0)
		lg--;
	if (lg > 14)			/* 2^(14+17) = 2⁳ⁱ */
		lg = 14;
	/* allocate larger output queues for higher-speed interfaces */
	bsz = 1UL << (lg + 17);		/* 2ⁱ⁷ = 128K, bsz = 2ⁿ × 128K */
	while (bsz > mainmem->maxsize / 8 && bsz > 128*1024)
		bsz /= 2;

	netifinit(ether, name, Ntypes, bsz);
>>	while (ether->oq == nil && bsz > 128*1024) {
		bsz /= 2;
		ether->oq = qopen(bsz, Qmsg, 0, 0);
		ether->limit = bsz;
	}
	if(ether->oq == nil)
		panic("etherreset %s", name);

the simple fix would be to change the > on the marked
line to >=.  but i think the while loop could be tossed
since malloc panics on failure and since qopen only allocates
sizeof(Queue) regardless of the limit argument.  i had
this code when i wrote the myricom driver (qio sets q->limit itself).

	j = ether->mbps;
	if(j > 1000)
		j *= 10;
	for(i = 0; j >= 100; i++)
		j /= 10;
	i = (128<<i) * 1024;
	netifinit(ether, name, Ntypes, i);
	if(ether->oq == nil)
		ether->oq = qopen(i, Qmsg, 0, 0);
	if(ether->oq == nil)
		panic("etherreset %s", name);

by the way, a quick scan shows
	ether2114x
	etherrhine
are capable of setting mbps to 0 on startup.  this should
be legal, since ethernet can be connected after boot.

- erik