On Thu, Aug 1, 2024 at 6:56 PM Ge Yang <yangge1116@xxxxxxx> wrote:
>
>
>
> >> I can't reproduce this problem, using tmpfs to compile linux.
> >> Seems you limit the memory size used to compile linux, which leads to
> >> OOM. May I ask why the memory size is limited to 481280kB? Do I also
> >> need to limit the memory size to 481280kB to test?
> >
> > Yes, you need to limit the cgroup memory size to force the swap
> > action. I am using memory.max = 470M.
> >
> > I believe other values e.g. 800M can trigger it as well. The reason to
> > limit the memory to cause the swap action.
> > The goal is to intentionally overwhelm the memory load and let the
> > swap system do its job. The 470M is chosen to cause a lot of swap
> > action but not too high to cause OOM kills in normal kernels.
> > In another word, high enough swap pressure but not too high to bust
> > into OOM kill. e.g. I verify that, with your patch reverted, the
> > mm-stable kernel can sustain this level of swap pressure (470M)
> > without OOM kill.
> >
> > I borrowed the 470M magic value from Hugh and verified it works with
> > my test system. Huge has a similar swab test up which is more
> > complicated than mine. It is the inspiration of my swap stress test
> > setup.
> >
> > FYI, I am using "make -j32" on a machine with 12 cores (24
> > hyperthreading). My typical swap usage is about 3-5G. I set my
> > swapfile size to about 20G.
> > I am using zram or ssd as the swap backend. Hope that helps you
> > reproduce the problem.
> >
> Hi Chris,
>
> I try to construct the experiment according to your suggestions above.
Hi Ge,
Sorry to hear that you were not able to reproduce it.
> High swap pressure can be triggered, but OOM can't be reproduced. The
> specific steps are as follows:
> root@ubuntu-server-2204:/home/yangge# cp workspace/linux/ /dev/shm/ -rf
I use a slightly different way to setup the tmpfs:
Here is section of my script:
if ! [ -d $tmpdir ]; then
sudo mkdir -p $tmpdir
sudo mount -t tmpfs -o size=100% nodev $tmpdir
fi
sudo mkdir -p $cgroup
sudo sh -c "echo $mem > $cgroup/memory.max" || echo setup
memory.max error
sudo sh -c "echo 1 > $cgroup/memory.oom.group" || echo setup
oom.group error
Per run:
# $workdir is under $tmpdir
sudo rm -rf $workdir
mkdir -p $workdir
cd $workdir
echo "Extracting linux tree"
XZ_OPT='-T0 -9 –memory=75%' tar xJf $linux_src || die "xz
extract failed"
sudo sh -c "echo $BASHPID > $cgroup/cgroup.procs"
echo "Cleaning linux tree, setup defconfig"
cd $workdir/linux
make -j$NR_TASK clean
make defconfig > /dev/null
echo Kernel compile run $i
/usr/bin/time -a -o $log make --silent -j$NR_TASK || die "make failed"
> root@ubuntu-server-2204:/home/yangge# sync
> root@ubuntu-server-2204:/home/yangge# echo 3 > /proc/sys/vm/drop_caches
> root@ubuntu-server-2204:/home/yangge# cd /sys/fs/cgroup/
> root@ubuntu-server-2204:/sys/fs/cgroup/# mkdir kernel-build
> root@ubuntu-server-2204:/sys/fs/cgroup/# cd kernel-build
> root@ubuntu-server-2204:/sys/fs/cgroup/kernel-build# echo 470M > memory.max
> root@ubuntu-server-2204:/sys/fs/cgroup/kernel-build# echo $$ > cgroup.procs
> root@ubuntu-server-2204:/sys/fs/cgroup/kernel-build# cd /dev/shm/linux/
> root@ubuntu-server-2204:/dev/shm/linux# make clean && make -j24
I am using make -j 32.
Your step should work.
Did you enable MGLRU in your .config file? Mine did. I attached my
config file here.
>
> Please help to see which step does not meet your requirements.
How many cores does your server have? I assume your RAM should be
plenty on that server.
Chris
Attachment:
config
Description: Binary data
