On 2018/8/31 17:39, Sahitya Tummala wrote:
> When dev is busy, discard thread wake up timeout can be aligned with the
> exact time that it needs to wait for dev to come out of busy. This helps
> to avoid unnecessary periodic wakeups and thus save some power.
>
> Signed-off-by: Sahitya Tummala <[email protected]>
> ---
> fs/f2fs/segment.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8bcbb50..df14030 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1379,6 +1379,8 @@ static int issue_discard_thread(void *data)
> struct discard_policy dpolicy;
> unsigned int wait_ms = DEF_MIN_DISCARD_ISSUE_TIME;
> int issued;
> + unsigned long interval = sbi->interval_time[REQ_TIME] * HZ;
> + long delta;
>
> set_freezable();
>
> @@ -1410,7 +1412,11 @@ static int issue_discard_thread(void *data)
> __wait_all_discard_cmd(sbi, &dpolicy);
> wait_ms = dpolicy.min_interval;
> } else if (issued == -1){
> - wait_ms = dpolicy.mid_interval;
> + delta = (sbi->last_time[REQ_TIME] + interval) - jiffies;
I agree that we need to consider power consumption. One more consideration is
that discard thread may need different submission frequency comparing to garbage
collection thread, maybe a little fast, would it be better to split
sbi->interval_time[REQ_TIME] according to gc/discard type.
How do you think?
Thanks,
> + if (delta > 0)
> + wait_ms = jiffies_to_msecs(delta);
> + else
> + wait_ms = dpolicy.mid_interval;
> } else {
> wait_ms = dpolicy.max_interval;
> }
>
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