• Kemeng Shi's avatar
    blk-throttle: correct calculation of wait time in tg_may_dispatch · 183daeb1
    Kemeng Shi authored
    In C language, When executing "if (expression1 && expression2)" and
    expression1 return false, the expression2 may not be executed.
    For "tg_within_bps_limit(tg, bio, bps_limit, &bps_wait) &&
    tg_within_iops_limit(tg, bio, iops_limit, &iops_wait))", if bps is
    limited, tg_within_bps_limit will return false and
    tg_within_iops_limit will not be called. So even bps and iops are
    both limited, iops_wait will not be calculated and is always zero.
    So wait time of iops is always ignored.
    
    Fix this by always calling tg_within_bps_limit and tg_within_iops_limit
    to get wait time for both bps and iops.
    
    Observed that:
    1. Wait time in tg_within_iops_limit/tg_within_bps_limit need always
    be stored as wait argument is always passed.
    2. wait time is stored to zero if iops/bps is limited otherwise non-zero
    is stored.
    Simpfy tg_within_iops_limit/tg_within_bps_limit by removing wait argument
    and return wait time directly. Caller tg_may_dispatch checks if wait time
    is zero to find if iops/bps is limited.
    Acked-by: default avatarTejun Heo <tj@kernel.org>
    Signed-off-by: default avatarKemeng Shi <shikemeng@huawei.com>
    Link: https://lore.kernel.org/r/20221205115709.251489-5-shikemeng@huaweicloud.comSigned-off-by: default avatarJens Axboe <axboe@kernel.dk>
    183daeb1
blk-throttle.c 66.7 KB