Date: Wed, 24 Oct 2012 14:26:43 +0000 (UTC) From: Vadim Goncharov <vadim_nuclight@mail.ru> To: freebsd-current@freebsd.org Cc: freebsd-net@freebsd.org Subject: maxusers (thus mbuf etc.) autotuning capped at 384 Message-ID: <slrnk8ful4.386.vadim_nuclight@kernblitz.nuclight.ipfw.ru>
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Hi,
We have 'maxusers' tunable which affects many other tunables, e.g. number of
network mbuf/clusters which is often too low on current machines.
There is code in sys/kern/subr_param.c:
if (maxusers == 0) {
maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
if (maxusers < 32)
maxusers = 32;
if (maxusers > 384)
maxusers = 384;
}
It was capped to 384 for i386 KVM size limits in r89769, so that amd64, not
constrained to 1Gb KVA, suffers from this. I suspect that 384 may be wrong even
for i386 today, but let's be conservative and limit maxusers to 384 per 1 Gb of
KVM, like this:
#define _MAX_MAXUSERS (((VM_MAX_KERNEL_ADDRESS - \
KERNBASE) / (8 * 1024 * 1024)) * 3)
if (maxusers == 0) {
maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE);
if (maxusers < 32)
maxusers = 32;
if (maxusers > _MAX_MAXUSERS)
maxusers = _MAX_MAXUSERS;
}
#undef _MAX_MAXUSERS
Any better ideas?
--
WBR, Vadim Goncharov. ICQ#166852181 mailto:vadim_nuclight@mail.ru
[Anti-Greenpeace][Sober FreeBSD zealot][http://nuclight.livejournal.com]
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