Hi.
I came across serious performance degradation when adding many tps. I'm
using following script:
------------------------------------------------------------------------
#!/bin/bash
dev=testdummy
ip link add name $dev type dummy
ip link set dev $dev up
tc qdisc add dev $dev ingress
tmp_file_name=$(date +"/tmp/tc_batch.%s.%N.tmp")
pref_id=1
while [ $pref_id -lt 20000 ]
do
echo "filter add dev $dev ingress proto ip pref $pref_id matchall
action drop" >> $tmp_file_name
((pref_id++))
done
start=$(date +"%s")
tc -b $tmp_file_name
stop=$(date +"%s")
echo "Insertion duration: $(($stop - $start)) sec"
rm -f $tmp_file_name
ip link del dev $dev
------------------------------------------------------------------------
On my testing vm, result on 5.1 kernel is:
Insertion duration: 3 sec
On net-next this is:
Insertion duration: 54 sec
I did simple prifiling using perf. Output on 5.1 kernel:
77.85% tc [kernel.kallsyms] [k] tcf_chain_tp_find
3.30% tc [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
1.33% tc_pref_scale.s [kernel.kallsyms] [k] do_syscall_64
0.60% tc_pref_scale.s libc-2.28.so [.] malloc
0.55% tc [kernel.kallsyms] [k] mutex_spin_on_owner
0.51% tc libc-2.28.so [.] __memset_sse2_unaligned_erms
0.40% tc_pref_scale.s libc-2.28.so [.]
__gconv_transform_utf8_internal
0.38% tc_pref_scale.s libc-2.28.so [.] _int_free
0.37% tc_pref_scale.s libc-2.28.so [.] __GI___strlen_sse2
0.37% tc [kernel.kallsyms] [k] idr_get_free
Output on net-next:
39.26% tc [kernel.vmlinux] [k] lock_is_held_type
33.99% tc [kernel.vmlinux] [k] tcf_chain_tp_find
12.77% tc [kernel.vmlinux] [k] __asan_load4_noabort
1.90% tc [kernel.vmlinux] [k] __asan_load8_noabort
1.08% tc [kernel.vmlinux] [k] lock_acquire
0.94% tc [kernel.vmlinux] [k] debug_lockdep_rcu_enabled
0.61% tc [kernel.vmlinux] [k]
debug_lockdep_rcu_enabled.part.5
0.51% tc [kernel.vmlinux] [k] unwind_next_frame
0.50% tc [kernel.vmlinux] [k] _raw_spin_unlock_irqrestore
0.47% tc_pref_scale.s [kernel.vmlinux] [k] lock_acquire
0.47% tc [kernel.vmlinux] [k] lock_release
I didn't investigate this any further now. I fear that this might be
related to Vlad's changes in the area. Any ideas?
Thanks!
Jiri
