From: Michal Hocko <mhocko@suse.com>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Dave Hansen <dave.hansen@intel.com>,
Ying Huang <ying.huang@intel.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] mm: Fix dropped memcg from mem cgroup soft limit tree
Date: Thu, 18 Feb 2021 20:13:05 +0100 [thread overview]
Message-ID: <YC68QRVsCONXscCl@dhcp22.suse.cz> (raw)
In-Reply-To: <c3ffa2cb-cb2c-20b7-d722-c875934992e9@linux.intel.com>
On Thu 18-02-21 10:30:20, Tim Chen wrote:
>
>
> On 2/18/21 12:24 AM, Michal Hocko wrote:
>
> >
> > I have already acked this patch in the previous version along with Fixes
> > tag. It seems that my review feedback has been completely ignored also
> > for other patches in this series.
>
> Michal,
>
> My apology. Our mail system screwed up and there are some mail missing
> from our mail system that I completely missed your mail.
> Only saw them now after I looked into the lore.kernel.org.
I see. My apology for suspecting you from ignoring my review.
> Responding to your comment:
>
> >Have you observed this happening in the real life? I do agree that the
> >threshold based updates of the tree is not ideal but the whole soft
> >reclaim code is far from optimal. So why do we care only now? The
> >feature is essentially dead and fine tuning it sounds like a step back
> >to me.
>
> Yes, I did see the issue mentioned in patch 2 breaking soft limit
> reclaim for cgroup v1. There are still some of our customers using
> cgroup v1 so we will like to fix this if possible.
It would be great to see more details.
> For patch 3 regarding the uncharge_batch, it
> is more of an observation that we should uncharge in batch of same node
> and not prompted by actual workload.
> Thinking more about this, the worst that could happen
> is we could have some entries in the soft limit tree that overestimate
> the memory used. The worst that could happen is a soft page reclaim
> on that cgroup. The overhead from extra memcg event update could
> be more than a soft page reclaim pass. So let's drop patch 3
> for now.
I would still prefer to handle that in the soft limit reclaim path and
check each memcg for the soft limit reclaim excess before the reclaim.
> Let me know if you will like me to resend patch 1 with the fixes tag
> for commit 4e41695356fb ("memory controller: soft limit reclaim on contention")
> and if there are any changes I should make for patch 2.
I will ack and suggest Fixes.
>
> Thanks.
>
> Tim
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-02-18 19:13 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 20:41 [PATCH v2 0/3] Soft limit memory management bug fixes Tim Chen
2021-02-17 20:41 ` [PATCH v2 1/3] mm: Fix dropped memcg from mem cgroup soft limit tree Tim Chen
2021-02-18 8:24 ` Michal Hocko
2021-02-18 18:30 ` Tim Chen
2021-02-18 19:13 ` Michal Hocko [this message]
2021-02-18 19:51 ` Tim Chen
2021-02-18 19:13 ` Michal Hocko
2021-03-04 17:35 ` Tim Chen
2021-03-05 9:11 ` Michal Hocko
2021-03-05 19:07 ` Tim Chen
2021-03-08 8:34 ` Michal Hocko
2021-02-17 20:41 ` [PATCH v2 2/3] mm: Force update of mem cgroup soft limit tree on usage excess Tim Chen
2021-02-19 9:11 ` Michal Hocko
2021-02-19 18:59 ` Tim Chen
2021-02-20 16:23 ` Tim Chen
2021-02-22 8:40 ` Michal Hocko
2021-02-22 17:41 ` Tim Chen
2021-02-22 19:09 ` Michal Hocko
2021-02-22 19:23 ` Tim Chen
2021-02-22 19:48 ` Tim Chen
2021-02-24 11:53 ` Michal Hocko
2021-02-25 22:48 ` Tim Chen
2021-02-26 8:52 ` Michal Hocko
2021-02-27 0:56 ` Tim Chen
2021-03-01 7:39 ` Michal Hocko
2021-02-25 22:25 ` Tim Chen
2021-03-02 6:25 ` [mm] 4f09feb8bf: vm-scalability.throughput -4.3% regression kernel test robot
2021-02-17 20:41 ` [PATCH v2 3/3] mm: Fix missing mem cgroup soft limit tree updates Tim Chen
2021-02-18 5:56 ` Johannes Weiner
2021-02-22 18:38 ` Tim Chen
2021-02-23 15:18 ` Johannes Weiner
2021-02-19 9:16 ` Michal Hocko
2021-02-19 19:28 ` Tim Chen
2021-02-22 8:41 ` Michal Hocko
2021-02-22 17:45 ` Tim Chen
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