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From: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
To: Roman Gushchin <roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>
Cc: "Shakeel Butt" <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	"Johannes Weiner"
	<hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	"Muchun Song"
	<songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
	"Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org>,
	"Eric Dumazet" <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	"Soheil Hassas Yeganeh"
	<soheil-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	"Feng Tang" <feng.tang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	"Oliver Sang"
	<oliver.sang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	"Andrew Morton"
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	lkp-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 3/3] memcg: increase MEMCG_CHARGE_BATCH to 64
Date: Mon, 22 Aug 2022 21:34:59 +0200	[thread overview]
Message-ID: <YwPZ1lpJ98pZSLmw@dhcp22.suse.cz> (raw)
In-Reply-To: <YwPM6o1+pZ2kRyy3@P9FQF9L96D>

On Mon 22-08-22 11:37:30, Roman Gushchin wrote:
[...]
> I wonder only if we want to make it configurable (Idk a sysctl or maybe
> a config option) and close the topic.

I do not think this is a good idea. We have other examples where we have
outsourced internal tunning to the userspace and it has mostly proven
impractical and long term more problematic than useful (e.g.
lowmem_reserve_ratio, percpu_pagelist_high_fraction, swappiness just to
name some that come to my mind). I have seen more often these to be used
incorrectly than useful.

In this case, I guess we should consider either moving to per memcg
charge batching and see whether the pcp overhead x memcg_count is worth
that or some automagic tuning of the batch size depending on how
effectively the batch is used. Certainly a lot of room for
experimenting.

-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2022-08-22 19:34 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-22  0:17 [PATCH 0/3] memcg: optimizatize charge codepath Shakeel Butt
     [not found] ` <20220822001737.4120417-1-shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2022-08-22  0:17   ` [PATCH 1/3] mm: page_counter: remove unneeded atomic ops for low/min Shakeel Butt
2022-08-22  9:55     ` Michal Hocko
     [not found]       ` <YwNSlZFPMgclrSCz-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2022-08-22 10:18         ` Michal Hocko
2022-08-22 14:55           ` Shakeel Butt
2022-08-22 15:20             ` Michal Hocko
     [not found]               ` <YwOeocdkF/lacpKn-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2022-08-22 16:06                 ` Shakeel Butt
2022-08-23  9:42                 ` Michal Hocko
     [not found]     ` <20220822001737.4120417-2-shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2022-08-22  0:20       ` Soheil Hassas Yeganeh
2022-08-22  2:39       ` Feng Tang
2022-08-22 18:23       ` Roman Gushchin
2022-08-22  0:17 ` [PATCH 2/3] mm: page_counter: rearrange struct page_counter fields Shakeel Butt
     [not found]   ` <20220822001737.4120417-3-shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2022-08-22  0:24     ` Soheil Hassas Yeganeh
2022-08-22  4:55       ` Shakeel Butt
2022-08-22 13:06         ` Soheil Hassas Yeganeh
2022-08-22  2:10     ` Feng Tang
2022-08-22  4:59       ` Shakeel Butt
2022-08-22 10:23     ` Michal Hocko
2022-08-22 15:06       ` Shakeel Butt
     [not found]         ` <CALvZod5pw_7hnH44hdC3rDGQxQB2XATrViNNGosG3FnUoWo-4A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2022-08-22 15:15           ` Michal Hocko
2022-08-22 16:04             ` Shakeel Butt
     [not found]               ` <CALvZod4whYX+0ZuCGgyKuG-Q_9d0g7N_x+=WXOeB_1TM=3Q7vg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2022-08-22 18:27                 ` Roman Gushchin
2022-08-22  0:17 ` [PATCH 3/3] memcg: increase MEMCG_CHARGE_BATCH to 64 Shakeel Butt
     [not found]   ` <20220822001737.4120417-4-shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2022-08-22  0:24     ` Soheil Hassas Yeganeh
2022-08-22 10:47     ` Michal Hocko
2022-08-22 15:09       ` Shakeel Butt
2022-08-22 15:22         ` Michal Hocko
     [not found]           ` <YwOfP/6PtS8BxNhz-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2022-08-22 16:07             ` Shakeel Butt
2022-08-22 18:37     ` Roman Gushchin
2022-08-22 19:34       ` Michal Hocko [this message]
     [not found]         ` <YwPZ1lpJ98pZSLmw-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2022-08-23  2:22           ` Roman Gushchin
2022-08-23  4:49             ` Michal Hocko
2022-08-22  2:30   ` Feng Tang

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