Re: [PATCH] mm/vmscan: add sysctl knobs for protecting the working set

[ValdikSS <iam@valdikss.org.ru>]

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On 13.12.2021 11:38, Barry Song wrote:
> On Tue, Dec 7, 2021 at 5:47 AM ValdikSS <iam@valdikss.org.ru> wrote:
>>
>> This patchset is surprisingly effective and very useful for low-end PC
>> with slow HDD, single-board ARM boards with slow storage, cheap Android
>> smartphones with limited amount of memory. It almost completely prevents
>> thrashing condition and aids in fast OOM killer invocation.
>>
> 
> Can you please post your hardware information like what is the cpu, how much
> memory you have and also post your sysctl knobs, like how do you set
> vm.anon_min_kbytes,  vm.clean_low_kbytes and vm.clean_min_kbytes?

I have a typical office computer of year 2007:

* Motherboard: Gigabyte GA-945GCM-S2L (early LGA775 socket, GMA950 
integrated graphics, September 2007)
* 2 core 64 bit CPU: Intel® Core™2 Duo E4600 (2 cores, 2.4 GHz, late 2007)
* 2 GB of RAM (DDR2 667 MHz, single module)
* Very old and slow 160 GB Hard Disk: Samsung HD161HJ (SATA II, June 2007):
* No discrete graphics card

I used vm.clean_low_kbytes=384000 (384 MB) to keep most of file cache in 
memory, because the HDD is slow and every data re-read leads to 
uncomfortable freezes and slow work.

More information, including the video, is here: 
https://notes.valdikss.org.ru/linux-for-old-pc-from-2007/en/

> 
>> The similar file-locking patch is used in ChromeOS for nearly 10 years
>> but not on stock Linux or Android. It would be very beneficial for
>> lower-performance Android phones, SBCs, old PCs and other devices.
>>
> 
> Can you post the link of the similar file-locking patch?

Here's a patch: https://lkml.org/lkml/2010/10/28/289
Here's more in-depth description: https://lkml.org/lkml/2010/11/1/20

Please also note that another Google developer, Yu Zhao, has also made a 
modern version of this (ChromiumOS) patch called MGLRU, the goal of 
which is quite similar to le9 (the patch we're discussing here), but 
with "more brains":
https://lore.kernel.org/lkml/20220104202247.2903702-1-yuzhao@google.com/T/#m8fd2a29bc557d27d1000f837f65b6c930eef9dff

Please take a moment and read the information in the link above. Yu Zhao 
develops this patch for almost two years and knows the issue better than 
me, a casual user.


> 
>> With this patch, combined with zram, I'm able to run the following
>> software on an old office PC from 2007 with __only 2GB of RAM__
>> simultaneously:
>>
>>    * Firefox with 37 active tabs (all data in RAM, no tab unloading)
>>    * Discord
>>    * Skype
>>    * LibreOffice with the document opened
>>    * Two PDF files (14 and 47 megabytes in size)
>>
>> And the PC doesn't crawl like a snail, even with 2+ GB in zram!
>> Without the patch, this PC is barely usable.
>> Please watch the video:
>> https://notes.valdikss.org.ru/linux-for-old-pc-from-2007/en/
>>
> 
> The video was captured before using this patch? what video says
> "the result of the test computer after the configuration", what does
> "the configuration" mean?

The video was captured after the patch. Before the patch, it's basically 
not possible to use Firefox only with 20+ tabs because the PC enters 
thrashing condition and reacts so slow that even mouse cursor freezes 
frequently. The PC is absolutely unusable for any decent work without 
the patch, regardless of swappiness, vm.min_free_kbytes or any other 
tunables.

The configuration is this patch with vm.clean_low_kbytes=384000 and 150% 
zram. More information is provided on the website.

> 
> Thanks
> Barry

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