On Sat, Aug 12, 2006 at 10:56:31AM -0400, Rik van Riel (riel@redhat.com) wrote:

quoted

Yep. Socket allocations end up with alloc_skb() which is essentialy the
same as what is being done for receiving path skbs.
If you really want to separate critical from non-critical sockets, it is
much better not to play with alloc_skb() but directly forbid it in
appropriate socket allocation function like sock_alloc_send_skb().

The problem is the RECEIVE side.

quoted

What I suggested in previous e-mail is to separate networking
allocations from other system allocations, so problem in main allocator
and it's OOM would never affect network path.

That solves half of the problem.  We still need to make sure we
do not allocate memory to non-critical sockets when the system
is almost out of memory.

One must receive a packet to determine if that packet must be dropped
until tricky hardware with header split capabilities or MMIO copying is
used. Peter uses special pool to get data from when system is in OOM (at
least in his latest patchset), so allocations are separated and thus
network code is not affected by OOM condition, which allows to make
forward progress.
Critical flag can be setup through setsockopt() and checked in
tcp_v4_rcv().

-- 
	Evgeniy Polyakov