On Wed, Sep 02, 2020 at 06:37:43PM +0200, Pablo Neira Ayuso wrote: > On x86_64, each notification results in one skbuff allocation which > consumes at least 768 bytes due to the skbuff overhead. > > This patch coalesces several notifications into one single skbuff, so > each notification consumes at least ~211 bytes, that ~3.5 times less > memory consumption. As a result, this is reducing the chances to exhaust > the netlink socket receive buffer. > > Rule of thumb is that each notification batch only contains netlink > messages whose report flag is the same, nfnetlink_send() requires this > to do appropriately delivery to userspace, either via unicast (echo > mode) or multicast (monitor mode). > > The skbuff control buffer is used to annotate the report flag for later > handling at the new coalescing routine. > > The batch skbuff notification size is NLMSG_GOODSIZE, using a larger > skbuff would allow for more socket receiver buffer savings (to amortize > the cost of the skbuff even more), however, going over that size might > break userspace applications, so let's be conservative and stick to > NLMSG_GOODSIZE. > > Reported-by: Phil Sutter <phil@xxxxxx> > Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Acked-by: Phil Sutter <phil@xxxxxx> Thanks, Phil
