Hello Greg. [Hope I am not to late for this] On 16/10/2018 19:09, Greg Kroah-Hartman wrote: > 4.9-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Eric Dumazet <edumazet@xxxxxxxxxx> > > Some applications still rely on IP fragmentation, and to be fair linux > reassembly unit is not working under any serious load. > > It uses static hash tables of 1024 buckets, and up to 128 items per bucket (!!!) > > A work queue is supposed to garbage collect items when host is under memory > pressure, and doing a hash rebuild, changing seed used in hash computations. > > This work queue blocks softirqs for up to 25 ms when doing a hash rebuild, > occurring every 5 seconds if host is under fire. > > Then there is the problem of sharing this hash table for all netns. > > It is time to switch to rhashtables, and allocate one of them per netns > to speedup netns dismantle, since this is a critical metric these days. > > Lookup is now using RCU. A followup patch will even remove > the refcount hold/release left from prior implementation and save > a couple of atomic operations. > > Before this patch, 16 cpus (16 RX queue NIC) could not handle more > than 1 Mpps frags DDOS. > > After the patch, I reach 9 Mpps without any tuning, and can use up to 2GB > of storage for the fragments (exact number depends on frags being evicted > after timeout) > > $ grep FRAG /proc/net/sockstat > FRAG: inuse 1966916 memory 2140004608 > > A followup patch will change the limits for 64bit arches. > > Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> > Cc: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> > Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > Cc: Florian Westphal <fw@xxxxxxxxx> > Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx> > Cc: Alexander Aring <alex.aring@xxxxxxxxx> > Cc: Stefan Schmidt <stefan@xxxxxxxxxxxxxxx> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> > (cherry picked from commit 648700f76b03b7e8149d13cc2bdb3355035258a9) > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > --- > Documentation/networking/ip-sysctl.txt | 7 > include/net/inet_frag.h | 81 +++---- > include/net/ipv6.h | 16 - > net/ieee802154/6lowpan/6lowpan_i.h | 26 -- > net/ieee802154/6lowpan/reassembly.c | 91 +++----- > net/ipv4/inet_fragment.c | 349 ++++++-------------------------- > net/ipv4/ip_fragment.c | 112 ++++------ > net/ipv6/netfilter/nf_conntrack_reasm.c | 51 +--- > net/ipv6/reassembly.c | 110 ++++------ > 9 files changed, 267 insertions(+), 576 deletions(-) > When this patch hit master a while back we had to address a regression in the ieee802514 6lowpan layer. It seems this fix is missing in the backport series (only looking at your patchset here, no the full tree). https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=f18fa5de5ba7f1d6650951502bb96a6e4715a948 I would appreciate if you could pull this into this series as well. regards Stefan Schmidt
