Thank you for the answer. May be I explain my problem not so well :-( I don't have enabled swap partition in fstab and if I run swapon nothing is shown. The swap partition is not defined anywhere in the system. Only the manager is available in the kernel.
I made an analisys of memory usage before posting this, and I see that when the free ram drop under 600MB the kernel thread mmcq/2 and kswap0 starts to work. I see the this 600MB is 60% of 1GB, and vm.swapping=60. So I ask here if someone has some experience. with vm.swappiness value on embedded. You have centered perfecly the matter about the slow-down: when memory drop to low, the system is tired to work. I cannot explain why even if no swap spaces are defined, kswap0 works Now I try to put vm.swappiness=6 and it seems to work well MZ On mar 9 2021, at 12:17 pm, Laurent Gauthier <[email protected]> wrote: > Ciao Mauro, > > Sounds more like a pure Linux/UNIX question than a yocto one :-) > > As you most likely know on an embedded system which uses permanent storage > (NAND flash or eMMC) that is subject to wear it is important to completely > turn off swap. > > At runtime if the system is up and running then you should issue the "swapoff > -a" command. > > But the proper fix is to remove any entry from your /etc/fstab designating a > swap partition. > > However I would be surprised if you had a swap partition configured in your > system as most embedded systems don't have one. > > Instead what I am thinking is that you are likely seeing a system slow-down > due to your system's memory usage coming close to 100% of the available RAM, > which in turn causes all calls to memory allocation functions to slow down > (algorithms have to look harder to find available memory). > > I would suggest that when the issue occurs that you first check the current > system memory usage and have a look at which application is using the most > memory and figure out if there is a way to optimize it and reduce the memory > usage. > > Kind regards, Laurent. > On Tue, Mar 9, 2021 at 10:03 AM Mauro Ziliani <[email protected] > (mailto:[email protected])> wrote: > > Hi all. > > I'm working with Krogoth on a imx6dl board with 1GB of RAM. > > I don't setup the swap space, but sometimes I see that kswap0 task starts, > > and the board slow down. > > > > I'd like to change the value of vm.swappiness to avoid swap requests > > The default value of vm.swappiness is 60. > > There is a minimum value for vm.swappiness? > > Best regards, > > MZ > > > > > > > > > -- > Laurent Gauthier > Embedded Linux Systems & Software > Phone: +33 630 483 429 > https://soccasys.com > >
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