netdev - Re: [PATCH 13/14] mm: memcontrol: account socket memory in unified hierarchy memory controller

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Date:	Thu, 19 Nov 2015 14:50:24 +0100
From:	Michal Hocko <mhocko@...nel.org>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	David Miller <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Vladimir Davydov <vdavydov@...tuozzo.com>,
	Tejun Heo <tj@...nel.org>, netdev@...r.kernel.org,
	linux-mm@...ck.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH 13/14] mm: memcontrol: account socket memory in unified
 hierarchy memory controller

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
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