1. Home
  2. Raspberry Pi Group
  3. Question about ever growing swap space on raspi 4 4 GB
  4. Page 3

Question about ever growing swap space on raspi 4 4 GB

On a sunny day (Mon, 27 Jan 2020 20:01:23 +0000) it happened druck wrote in :

OK, thnak you. Better avoid it getting full! Seems OK now:

Fri 24 Jan 2020 03:10:42 PM CET: MiB Mem : 3906.0 total, 2891.6 free, 378.2 used, 636.2 buff/cache MiB Swap: 100.0 total, 20.4 free, 79.6 used. 3378.8 avail Mem

Sat 25 Jan 2020 06:46:05 AM CET MiB Mem : 3906.0 total, 2653.7 free, 372.0 used, 880.4 buff/cache MiB Swap: 100.0 total, 24.7 free, 75.3 used. 3380.4 avail Mem

Sun 26 Jan 2020 07:32:08 AM CET MiB Mem : 3906.0 total, 3265.9 free, 370.6 used, 269.5 buff/cache MiB Swap: 100.0 total, 26.9 free, 73.1 used. 3383.9 avail Mem

Mon 27 Jan 2020 07:01:17 AM CET MiB Mem : 3906.0 total, 3364.9 free, 372.7 used, 168.4 buff/cache MiB Swap: 100.0 total, 28.7 free, 71.3 used. 3382.6 avail Mem

Tue 28 Jan 2020 04:40:45 AM CET iB Mem : 3906.0 total, 2881.9 free, 374.7 used, 649.5 buff/cache MiB Swap: 100.0 total, 29.5 free, 70.5 used. 3375.7 avail Mem

Getting better!

So I will leave it running this way, Do not fix it if it works!

For the other poster, as the system is just writing video to disk using a shorter cache (by writing it more often to harddisk) has no bad side affects, the stuff will have to be written to disk anyways. In fact the writing periods will be more often and shorter, but it is the same amount of data, Writing to disk more often causes less long interrupts and keeps more memory available.

In fact Linux caching results in a high video delay on some of my systems (PCs)!

20 seconds for mcamip is normal!

Also it is a security risk, in case of a power failure you lose the last (likely most important part where you see the bad guy cutting the cables) 20 seconds.

Reply to
Jan Panteltje
Loading thread data ...

thats a serious error

--
?It is dangerous to be right in matters on which the established  
authorities are wrong.? 

? Voltaire, The Age of Louis XIV
Reply to
The Natural Philosopher

Nope malloc succeeds and processes get a SEGV when they try to map memory that can't be found.

That is the designed response to out of memory conditions on every flavour of unix I know, what else would you suggest ?

--
Steve O'Hara-Smith                          |   Directable Mirror Arrays 
C:\>WIN                                     | A better way to focus the sun 
The computer obeys and wins.                |    licences available see 
You lose and Bill collects.                 |    http://www.sohara.org/
Reply to
Ahem A Rivet's Shot

I wouldn't. I am not saying the behaviour is wrong or inappropriate, just that it is in fact always pretty *serious*.

It is te last ditch attempt to prevent a system crashing altogether: and in most cases a hard reboot is a pragmatic option.

--
"Nature does not give up the winter because people dislike the cold." 

? Confucius
Reply to
The Natural Philosopher

Look at /etc/dphys-swapfile and man dphys-swapfile AFAIK it checks the swap file on startup. Not there => create; already there => check if size as requested.

--

Chris Elvidge, England
Reply to
Chris Elvidge

Fair enough, it is of course.

Yep.

--
Steve O'Hara-Smith                          |   Directable Mirror Arrays 
C:\>WIN                                     | A better way to focus the sun 
The computer obeys and wins.                |    licences available see 
You lose and Bill collects.                 |    http://www.sohara.org/
Reply to
Ahem A Rivet's Shot

Not on all systems: neither the manpage nor /etc/dphys-swapfile exist on this Fedora system - but maybe thats because it has a swap partition.

--
Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie

dphys-swapfile (as I said earlier) is a Raspbian (Debian/Ubuntu) artifact. I can't see why it should exist on Fedora (RedHat?).

--

Chris Elvidge, England
Reply to
Chris Elvidge

And it usually kills a process that is the last one you'd choose yourself ...

Reply to
Andy Burns

Not a huge problem as it tends to be pretty random reads and writes of page sized data. It wouldn't make much difference even with a swap partition, which would be a single continuous area.

That is the big problem with swap on flash, but its the pattern of random accesses rather than fragmentation of the file which gives such bad performance.

---druck

Reply to
druck

I missed the 'Debian-only' notice - sorry 'bout that.

--
Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie

A prime example of Sod's Law.

-- Steve O'Hara-Smith | Directable Mirror Arrays C:\>WIN | A better way to focus the sun The computer obeys and wins. | licences available see You lose and Bill collects. |

formatting link

Reply to
Ahem A Rivet's Shot

Why is it that when something is lost its always in the last place you look?

--
?The ultimate result of shielding men from the effects of folly is to  
fill the world with fools.? 

Herbert Spencer
Reply to
The Natural Philosopher

Because you stop looking when you find it of course.

--
Steve O'Hara-Smith                          |   Directable Mirror Arrays 
C:\>WIN                                     | A better way to focus the sun 
The computer obeys and wins.                |    licences available see 
You lose and Bill collects.                 |    http://www.sohara.org/
Reply to
Ahem A Rivet's Shot

The question that nobody ever asks is:

"Why did yo start looking in the wrong place?".

--
Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie

Leading question. The real question is 'why wasn't it IN the right place?

--
There?s a mighty big difference between good, sound reasons and reasons  
that sound good. 

Burton Hillis (William Vaughn, American columnist)
Reply to
The Natural Philosopher

...probably both questions have the same answer.

--
Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie

;-)

--
-michael - NadaNet 3.1 and AppleCrate II:  http://michaeljmahon.com
Reply to
Michael J. Mahon

I got me a 4B 4Gig, and bought me tiny 128 Gig USB plug, stuck it into the back, configured sufficient Swap space on it and added it to fstab.

Was going to hook one of my 1T SSD USB-3 drives in but when I compiled a reasonably large program with make -j4 I noticed it didn't even use any swap space at all :-)-O so I'll probably just leave the plug in.

el

[...] 
--
if you want to reply, replace nospam with my initials
Reply to
Dr Eberhard Lisse

I had one of those, and tried it in the Pi, but it got alarmingly hot when in use. Instead I use a Samsung USB 3.1 bar drive, which is larger and made of metal, so dissipates any heat very quickly.

---druck

Reply to
druck

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.