On 2025/11/21 18:33, Sun Shaojie wrote:
> Hi, Ridong,
>
> Thu, 20 Nov 2025 21:25:12, Chen Ridong wrote:
>> On 2025/11/20 21:07, Sun Shaojie wrote:
>>> I don't understand the "order of operations" mentioned here. After reviewing
>>> the previous email content, are you referring to this?
>>>
>>> On Sat, 15 Nov 2025 15:41:03, Chen Ridong wrote:
>>>> With the result you expect, would we observe the following behaviors:
>>>>
>>>> #1> mkdir -p A1
>>>> #2> mkdir -p B1
>>>> #3> echo "0-1" > A1/cpuset.cpus
>>>> #4> echo "1-2" > B1/cpuset.cpus
>>>> #5> echo "root" > A1/cpuset.cpus.partition
>>>> #6> echo "root" > B1/cpuset.cpus.partition # A1:root;B1:root invalid
>>>>
>>>> #1> mkdir -p A1
>>>> #2> mkdir -p B1
>>>> #3> echo "0-1" > A1/cpuset.cpus
>>>> #4> echo "1-2" > B1/cpuset.cpus
>>>> #5> echo "root" > B1/cpuset.cpus.partition
>>>> #6> echo "root" > A1/cpuset.cpus.partition # A1:root invalid;B1:root
>>>>
>>>> Do different operation orders yield different results? If so, this is not
>>>> what we expect.
>>>
>>> However, after applying this patch, the outcomes of these two examples are
>>> as follows:
>>>
>>> #1> mkdir -p A1
>>> #2> mkdir -p B1
>>> #3> echo "0-1" > A1/cpuset.cpus | member | member |
>>> #4> echo "1-2" > B1/cpuset.cpus | member | member |
>>> #5> echo "root" > A1/cpuset.cpus.partition | root invalid | root |
>>> #6> echo "root" > B1/cpuset.cpus.partition | root invalid | root invalid|
>>>
>>> #1> mkdir -p A1
>>> #2> mkdir -p B1
>>> #3> echo "0-1" > A1/cpuset.cpus | member | member |
>>> #4> echo "1-2" > B1/cpuset.cpus | member | member |
>>> #5> echo "root" > B1/cpuset.cpus.partition | root | root invalid|
>>> #6> echo "root" > A1/cpuset.cpus.partition | root invalid | root invalid|
>>>
>>
>> How about the following two sequences of operations:
>>
>> #1> mkdir -p A1
>> #2> mkdir -p B1
>> #3> echo "0-1" > A1/cpuset.cpus
>> #4> echo "root" > A1/cpuset.cpus.partition
>> #5> echo "1-2" > B1/cpuset.cpus
>> #6> echo "root" > B1/cpuset.cpus.partition
>>
>>
>> #1> mkdir -p A1
>> #2> mkdir -p B1
>> #5> echo "1-2" > B1/cpuset.cpus
>> #6> echo "root" > B1/cpuset.cpus.partition
>> #3> echo "0-1" > A1/cpuset.cpus
>> #4> echo "root" > A1/cpuset.cpus.partition
>>
>> Will these two sequences yield the same result?
>
>> As a key requirement: Regardless of the order in which we apply the
>> configurations, identical final
>> settings should always result in identical system states. We need to confirm
>> if this holds true here.
>
> Is this truly a key requirement? It appears this requirement wasn't met even
> before applying my patch.
>
I believe it requires, it may some corner cases we should fix.
> The example below, which does not use this patch, demonstrates how different
> sequences with identical configurations can still lead to different system
> states.
>
> #1> mkdir -p A1
> #2> mkdir -p B1 | A1's prstate | B1's prstate |
> #3> echo "0-1" > A1/cpuset.cpus | member | member |
> #4> echo "0-1" > A1/cpuset.cpus.exclusive | member | member |
> #5> echo "root" > A1/cpuset.cpus.partition | root | member |
> #6> echo "1-2" > B1/cpuset.cpus | root invalid | member |
> #7> echo "2-3" > B1/cpuset.cpus.exclusive | root invalid | member |
> #8> echo "root" > B1/cpuset.cpus.partition | root invalid | root |
>
IIUC, you've created this example with the expectation that both A1 and B1
should serve as root
partitions. However, we currently lack a mechanism where modifying a cpuset's
state (e.g., cpus,
cpus.exclusive, or cpus.partition) can transition its sibling from an invalid
to a valid partition.
The behavior observed before step #6 is acceptable. Proactively setting B1 as a
partition in step #8
is permitted, given that B1 does not conflict with A1. However, we do not have
a mechanism to
passively and automatically transition A1 to a valid partition state.
> #1> mkdir -p A1
> #2> mkdir -p B1 | A1's prstate | B1's prstate |
> #3> echo "0-1" > A1/cpuset.cpus | member | member |
> #4> echo "0-1" > A1/cpuset.cpus.exclusive | member | member |
> #5> echo "2-3" > B1/cpuset.cpus.exclusive | member | member |
> #6> echo "root" > A1/cpuset.cpus.partition | root | member |
> #7> echo "1-2" > B1/cpuset.cpus | root | member |
> #8> echo "root" > B1/cpuset.cpus.partition | root | root |
>
> Even without this patch, the result can still differ.
>
>
> Thanks,
> Sun Shaojie
--
Best regards,
Ridong
