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From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
To: Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@kernel.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
	l.roehrs@profihost.ag, cgroups@vger.kernel.org,
	Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: lot of MemAvailable but falling cache and raising PSI
Date: Mon, 30 Sep 2019 08:56:54 +0200
Message-ID: <d6740465-bf85-49f1-ae4e-0bf4780b96b0@profihost.ag> (raw)
In-Reply-To: <4f6f1bc9-08f4-d53a-8788-a761be769757@suse.cz>

Hi,

the current status is, that everything works well / fine since i
switched from CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS to
CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
Am 27.09.19 um 14:45 schrieb Vlastimil Babka:
> On 9/19/19 12:21 PM, Stefan Priebe - Profihost AG wrote:
>> Kernel 5.2.14 is now running since exactly 7 days and now we can easaly
>> view a trend i', not sure if i should post graphs.
>>
>> Cache size is continuously shrinking while memfree is rising.
>>
>> While there were 4,5GB free in avg in the beginnen we now have an avg of
>> 8GB free memory.
>>
>> Cache has shrinked from avg 24G to avg 18G.
>>
>> Memory pressure has rised from avg 0% to avg 0.1% - not much but if you
>> look at the graphs it's continuously rising while cache is shrinking and
>> memfree is rising.
> 
> Hi, could you try the patch below? I suspect you're hitting a corner
> case where compaction_suitable() returns COMPACT_SKIPPED for the
> ZONE_DMA, triggering reclaim even if other zones have plenty of free
> memory. And should_continue_reclaim() then returns true until twice the
> requested page size is reclaimed (compact_gap()). That means 4MB
> reclaimed for each THP allocation attempt, which roughly matches the
> trace data you preovided previously.
> 
> The amplification to 4MB should be removed in patches merged for 5.4, so
> it would be only 32 pages reclaimed per THP allocation. The patch below
> tries to remove this corner case completely, and it should be more
> visible on your 5.2.x, so please apply it there.

so i switched back to 4.19 LTS Kernel - as this is the kernel we run on
all our infrastructures. THP is now only in use von kvm host machines.
Your patch applies to 4.19 as well - but not sure if it is a good idea
to apply it to those machines.

Greets,
Stefan


  reply index

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-05 11:27 Stefan Priebe - Profihost AG
2019-09-05 11:40 ` Michal Hocko
2019-09-05 11:56   ` Stefan Priebe - Profihost AG
2019-09-05 16:28     ` Yang Shi
2019-09-05 17:26       ` Stefan Priebe - Profihost AG
2019-09-05 18:46         ` Yang Shi
2019-09-05 19:31           ` Stefan Priebe - Profihost AG
2019-09-06 10:08     ` Stefan Priebe - Profihost AG
2019-09-06 10:25       ` Vlastimil Babka
2019-09-06 18:52       ` Yang Shi
2019-09-07  7:32         ` Stefan Priebe - Profihost AG
2019-09-09  8:27       ` Michal Hocko
2019-09-09  8:54         ` Stefan Priebe - Profihost AG
2019-09-09 11:01           ` Michal Hocko
2019-09-09 12:08             ` Michal Hocko
2019-09-09 12:10               ` Stefan Priebe - Profihost AG
2019-09-09 12:28                 ` Michal Hocko
2019-09-09 12:37                   ` Stefan Priebe - Profihost AG
2019-09-09 12:49                     ` Michal Hocko
2019-09-09 12:56                       ` Stefan Priebe - Profihost AG
     [not found]                         ` <52235eda-ffe2-721c-7ad7-575048e2d29d@profihost.ag>
2019-09-10  5:58                           ` Stefan Priebe - Profihost AG
2019-09-10  8:29                           ` Michal Hocko
2019-09-10  8:38                             ` Stefan Priebe - Profihost AG
2019-09-10  9:02                               ` Michal Hocko
2019-09-10  9:37                                 ` Stefan Priebe - Profihost AG
2019-09-10 11:07                                   ` Michal Hocko
2019-09-10 12:45                                     ` Stefan Priebe - Profihost AG
2019-09-10 12:57                                       ` Michal Hocko
2019-09-10 13:05                                         ` Stefan Priebe - Profihost AG
2019-09-10 13:14                                           ` Stefan Priebe - Profihost AG
2019-09-10 13:24                                             ` Michal Hocko
2019-09-11  6:12                                               ` Stefan Priebe - Profihost AG
2019-09-11  6:24                                                 ` Stefan Priebe - Profihost AG
2019-09-11 13:59                                                   ` Stefan Priebe - Profihost AG
2019-09-12 10:53                                                     ` Stefan Priebe - Profihost AG
2019-09-12 11:06                                                       ` Stefan Priebe - Profihost AG
2019-09-11  7:09                                                 ` 5.3-rc-8 hung task in IO (was: Re: lot of MemAvailable but falling cache and raising PSI) Michal Hocko
2019-09-11 14:09                                                   ` Stefan Priebe - Profihost AG
2019-09-11 14:56                                                   ` Filipe Manana
2019-09-11 15:39                                                     ` Stefan Priebe - Profihost AG
2019-09-11 15:56                                                       ` Filipe Manana
2019-09-11 16:15                                                         ` Stefan Priebe - Profihost AG
2019-09-11 16:19                                                           ` Filipe Manana
2019-09-19 10:21                                                 ` lot of MemAvailable but falling cache and raising PSI Stefan Priebe - Profihost AG
2019-09-23 12:08                                                   ` Michal Hocko
2019-09-27 12:45                                                   ` Vlastimil Babka
2019-09-30  6:56                                                     ` Stefan Priebe - Profihost AG [this message]
2019-09-30  7:21                                                       ` Vlastimil Babka
2019-10-22  7:41                                                     ` Stefan Priebe - Profihost AG
2019-10-22  7:48                                                       ` Vlastimil Babka
2019-10-22 10:02                                                         ` Stefan Priebe - Profihost AG
2019-10-22 10:20                                                           ` Oscar Salvador
2019-10-22 10:21                                                           ` Vlastimil Babka
2019-10-22 11:08                                                             ` Stefan Priebe - Profihost AG
2019-09-10  5:41                       ` Stefan Priebe - Profihost AG
2019-09-09 11:49           ` Vlastimil Babka
2019-09-09 12:09             ` Stefan Priebe - Profihost AG
2019-09-09 12:21               ` Vlastimil Babka
2019-09-09 12:31                 ` Stefan Priebe - Profihost AG
2019-09-05 12:15 ` Vlastimil Babka
2019-09-05 12:27   ` Stefan Priebe - Profihost AG

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