On 13/07/2020 23:14, Guoqing Jiang wrote:
> diff --git a/block/blk-core.c b/block/blk-core.c
> index d9d632639bd1..036eb04782de 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1411,6 +1411,34 @@ static void update_io_ticks(struct hd_struct *part, unsigned long now, bool end)
> }
> }
>
> +#ifdef CONFIG_BLK_ADDITIONAL_DISKSTAT
> +/*
> + * Either account additional stat for request if req is not NULL or account for bio.
> + */
> +static void blk_additional_latency(struct hd_struct *part, const int sgrp,
> + struct request *req, unsigned long start_jiffies)
> +{
> + unsigned int idx;
> + unsigned long duration, now = READ_ONCE(jiffies);
> +
> + if (req)
> + duration = jiffies_to_nsecs(now) - req->start_time_ns;
> + else
> + duration = jiffies_to_nsecs(now - start_jiffies);
> +
> + duration /= NSEC_PER_MSEC;
> + duration /= HZ_TO_MSEC_NUM;
> + if (likely(duration > 0)) {
> + idx = ilog2(duration);
> + if (idx > ADD_STAT_NUM - 1)
> + idx = ADD_STAT_NUM - 1;
> + } else
> + idx = 0;
> + part_stat_inc(part, latency_table[idx][sgrp]);
> +
> +}
> +#endif
> +
> static void blk_account_io_completion(struct request *req, unsigned int bytes)
> {
> if (req->part && blk_do_io_stat(req)) {
> @@ -1440,6 +1468,9 @@ void blk_account_io_done(struct request *req, u64 now)
> part = req->part;
>
> update_io_ticks(part, jiffies, true);
> +#ifdef CONFIG_BLK_ADDITIONAL_DISKSTAT
> + blk_additional_latency(part, sgrp, req, 0);
> +#endif
Not commenting on the general idea here but only the code. The above introduces quite a
lot of ifdefs in code. Please at least move the #ifdef CONFIG_BLK_ADDITIONAL_DISKSTAT
into the function body of blk_additional_latency() so you don't need any ifdefs at the
call sites.
