On 2025/11/20 21:07, Sun Shaojie wrote:
> Hi, Ridong,
>
> On Thu, 20 Nov 2025 08:57:51, Chen Ridong wrote:
>> On 2025/11/19 21:20, Michal Koutný wrote:
>>> On Wed, Nov 19, 2025 at 06:57:49PM +0800, Sun Shaojie
>>> <[email protected]> wrote:
>>>> Table 2.1: Before applying this patch
>>>> Step | A1's prstate | B1's prstate |
>>>> #1> echo "0-1" > A1/cpuset.cpus | member | member |
>>>> #2> echo "root" > A1/cpuset.cpus.partition | root | member |
>>>> #3> echo "2" > B1/cpuset.cpus | root | member |
>>>> #4> echo "root" > B1/cpuset.cpus.partition | root | root |
>>>> #5> echo "1-2" > B1/cpuset.cpus | root invalid | root invalid |
>>>>
>>>> After step #4, B1 can exclusively use CPU 2. Therefore, at step #5,
>>>> regardless of what conflicting value B1 writes to cpuset.cpus, it will
>>>> always have at least CPU 2 available. This makes it unnecessary to mark
>>>> A1 as "root invalid".
>>>>
>>>> Table 2.2: After applying this patch
>>>> Step | A1's prstate | B1's prstate |
>>>> #1> echo "0-1" > A1/cpuset.cpus | member | member |
>>>> #2> echo "root" > A1/cpuset.cpus.partition | root | member |
>>>> #3> echo "2" > B1/cpuset.cpus | root | member |
>>>> #4> echo "root" > B1/cpuset.cpus.partition | root | root |
>>>> #5> echo "1-2" > B1/cpuset.cpus | root | root invalid |
>>>>
>>>> In summary, regardless of how B1 configures its cpuset.cpus, there will
>>>> always be available CPUs in B1's cpuset.cpus.effective. Therefore, there
>>>> is no need to change A1 from "root" to "root invalid".
>>>
>>> Admittedly, I don't like this change because it relies on implicit
>>> preference ordering between siblings (here first comes, first served)
>>
>> Agree. If we only invalidate the latter one, I think regardless of the
>> implementation approach, we
>> may end up with different results depending on the order of operations.
>
>
> 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.
> Moreover, even without applying this patch, the result remains the same,
> because modifying cpuset.cpus.partition does not disable its siblings'
> partitions.
>
> So, what are the specific issues that you believe would arise?
>
>
> Thanks,
> Sun Shaojie
--
Best regards,
Ridong
