Re: [PATCH 1/4] cfq-iosced: Remove the check for same cfq group fromallow_merge

[Gui Jianfeng]

Vivek Goyal wrote:
> o allow_merge() already checks if submitting task is pointing to same cfqq
>   as rq has been queued in. If everything is fine, we should not be having
>   a task in one cgroup and having a pointer to cfqq in other cgroup.
> 
>   Well I guess in some situations it can happen and that is, when a random
>   IO queue has been moved into root cgroup for group_isolation=0. In
>   this case, tasks's cgroup/group is different from where actually cfqq is,
>   but this is intentional and in this case merging should be allowed.
> 
>   The second situation is where due to close cooperator patches, multiple
>   processes can be sharing a cfqq. If everything implemented right, we should
>   not end up in a situation where tasks from different processes in different
>   groups are sharing the same cfqq as we allow merging of cooperating queues
>   only if they are in same group.
> 
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>

Reviewed-by: Gui Jianfeng <guijianfeng@xxxxxxxxxxxxxx>

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