[LTP] [PATCH v2 1/2] controllers/cpuacct: skip cpuacct_100_100 on small memory systems

[Krzysztof Kozlowski]

On 16/06/2021 09:28, Krzysztof Kozlowski wrote:
> On 16/06/2021 09:27, Krzysztof Kozlowski wrote:
>> On 15/06/2021 18:40, Cyril Hrubis wrote:
>>> Hi!
>>>> +check_free_memory()
>>>> +{
>>>> +	local memneeded
>>>> +	local memfree=`awk '/MemAvailable/ {print $2}' /proc/meminfo`
>>>> +
>>>> +	if [ $? -ne 0 ]; then
>>>> +		local memcached
>>>> +
>>>> +		memfree=`awk '/MemFree/ {print $2}' /proc/meminfo`
>>>> +		test $? || return 0
>>>> +
>>>> +		memcached=`awk '/MemCached/ {print $2}' /proc/meminfo`
>>>> +		test $? || return 0
>>>
>>> I do not think that something as basic as awk on /proc/meminfo here will
>>> fail...
>>
>> It's still nice pattern to check for return values but if you insist, I
>> can drop it.
>>
>>>
>>>> +		memfree=$((memfree + memcached))
>>>> +	fi
>>>> +
>>>> +	# On x86_64, each 100 of processes were using ~16 MB of memory,
>>>> +	# so try to estimate the needed free memory based on this.
>>>> +	memneeded=$((max * nbprocess * 16384 / 100))
>>>> +
>>>> +	if [ $memfree -lt $memneeded ]; then
>>>
>>> I would still add some memory margin to the memneeded here. At least
>>> add a hundred of megabytes before we do the check.
>>
>> Sure.
>>
>>>
>>>> +		tst_brk TCONF "not enough of free memory on this system (approximate need $memneeded kB, free $memfree kB)"
>>>> +	fi
>>>> +	tst_res TINFO "memory requirements fulfilled (approximate need $memneeded kB, free $memfree kB)"
>>>> +
>>>> +	return 0
>>>> +}
>>>> +
>>>> +check_limits()
>>>> +{
>>>> +	local realuid="$SUDO_UID"
>>>> +	local tasksneeded=$((max * nbprocess + 100))
>>>> +
>>>> +	if [ "$realuid" = "" ]; then
>>>> +		realuid=`id -u`
>>>> +		test $? || return 0
>>>> +	fi
>>>> +
>>>> +	local tasksmax=`systemctl show user-${real_uid}.slice | awk -F '=' '/TasksMax/ {print $2}'`
>>>> +	test $? || return 0
>>>> +
>>>> +	if [ $tasksmax -le $tasksneeded ]; then
>>>> +		tst_brk TCONF "limit of tasks is too low (approximate need $tasksneeded, limit $tasksmax)"
>>>> +	fi
>>>> +	tst_res TINFO "task limit fulfilled (approximate need $tasksneeded, limit $tasksmax)"
>>>
>>> Huh, is this really needed? The test is supposed to run under root. The
>>> user is supposed to login as a root or at least do 'su -' before
>>> executing LTP anyways.
>>
>> Yeah, because even root sessions (user-0.slice) have the PID limit set
>> by systemd.
>>
>> $ ssh root@....
>> $ grep . /sys/fs/cgroup/pids/user.slice/*/*
>> /sys/fs/cgroup/pids/user.slice/user-0.slice/cgroup.clone_children:0
>> /sys/fs/cgroup/pids/user.slice/user-0.slice/notify_on_release:0
>> /sys/fs/cgroup/pids/user.slice/user-0.slice/pids.current:5
>> /sys/fs/cgroup/pids/user.slice/user-0.slice/pids.events:max 0
>> /sys/fs/cgroup/pids/user.slice/user-0.slice/pids.max:5207
> 
> I forgot to mention: that's a default Ubuntu 20.04 LTS system on 2 GB
> RAM machine, with systemd 245.4-4ubuntu3.6.

Any further comments here or something to fix? I think there were no
objections to this patch, right?


Best regards,
Krzysztof