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    SubjectRe: [PATCH v2 1/4] blk-mq: use percpu csd to remote complete instead of per-rq csd
    On Thu, Jun 29, 2023 at 07:03:56PM +0800, chengming.zhou@linux.dev wrote:
    > From: Chengming Zhou <zhouchengming@bytedance.com>
    >
    > If request need to be completed remotely, we insert it into percpu llist,
    > and smp_call_function_single_async() if llist is empty previously.
    >
    > We don't need to use per-rq csd, percpu csd is enough. And the size of
    > struct request is decreased by 24 bytes.
    >
    > This way is cleaner, and looks correct, given block softirq is guaranteed to be
    > scheduled to consume the list if one new request is added to this percpu list,
    > either smp_call_function_single_async() returns -EBUSY or 0.
    >
    > Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
    > ---
    > v2:
    > - Change to use call_single_data_t, which avoid to use 2 cache lines
    > for 1 csd, as suggested by Ming Lei.
    > - Improve the commit log, the explanation is copied from Ming Lei.

    Reviewed-by: Ming Lei <ming.lei@redhat.com>

    Thanks,
    Ming

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