On Wed 18-11-15 16:48:22, Johannes Weiner wrote:
[...]
So I ran perf record -g -a netperf -t TCP_STREAM multiple times inside
a memory-controlled cgroup, but mostly mem_cgroup_charge_skmem() does
not show up in the profile at all. Once it was there with 0.00%.
OK, this sounds very good! This means that most workloads which are not
focusing solely on the network traffic shouldn't even notice. I can
imagine that workloads with high throughput demands would notice but I
would also expect them to disable the feature.
Could you add this information to the changelog, please?
I ran another test that downloads the latest kernel image from
kernel.org at 13MB/s (on my i5 laptop) and it looks like this:
0.02% 0.01% irq/44-iwlwifi [kernel.kallsyms] [k] mem_cgroup_charge_skmem
|
---mem_cgroup_charge_skmem
__sk_mem_schedule
tcp_try_rmem_schedule
tcp_data_queue
tcp_rcv_established
tcp_v4_do_rcv
tcp_v4_rcv
ip_local_deliver
ip_rcv
__netif_receive_skb_core
__netif_receive_skb
netif_receive_skb_internal
napi_gro_complete
The runs vary too much for this to be measurable in elapsed time.
--
Michal Hocko
SUSE Labs