• Pavel Begunkov's avatar
    io-wq: handle hashed writes in chains · 86f3cd1b
    Pavel Begunkov authored
    We always punt async buffered writes to an io-wq helper, as the core
    kernel does not have IOCB_NOWAIT support for that. Most buffered async
    writes complete very quickly, as it's just a copy operation. This means
    that doing multiple locking roundtrips on the shared wqe lock for each
    buffered write is wasteful. Additionally, buffered writes are hashed
    work items, which means that any buffered write to a given file is
    serialized.
    
    Keep identicaly hashed work items contiguously in @wqe->work_list, and
    track a tail for each hash bucket. On dequeue of a hashed item, splice
    all of the same hash in one go using the tracked tail. Until the batch
    is done, the caller doesn't have to synchronize with the wqe or worker
    locks again.
    Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
    Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    86f3cd1b
io-wq.h 3.65 KB