lkml.org 
[lkml]   [2022]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 04/11] blk-throttle: correct calculation of wait time in tg_may_dispatch
    On Wed, Nov 23, 2022 at 02:03:54PM +0800, Kemeng Shi wrote:
    > If bps and iops both reach limit, we always return bps wait time as
    > tg_within_iops_limit is after "tg_within_bps_limit(tg, bio, bps_limit) &&"
    > and will not be called if tg_within_bps_limit return true.

    Maybe it's obvious but it'd be better to explain "why" this change is being
    made.

    > @@ -939,8 +926,9 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
    > jiffies + tg->td->throtl_slice);
    > }
    >
    > - if (tg_within_bps_limit(tg, bio, bps_limit, &bps_wait) &&
    > - tg_within_iops_limit(tg, bio, iops_limit, &iops_wait)) {
    > + bps_wait = tg_within_bps_limit(tg, bio, bps_limit);
    > + iops_wait = tg_within_iops_limit(tg, bio, iops_limit);
    > + if (bps_wait + iops_wait == 0) {
    > if (wait)
    > *wait = 0;
    > return true;

    So, max_wait is supposed to be maximum in the whole traversal path in the
    tree, not just the max value in this tg, so after this, the code should be
    changed to sth like the following, right?

    max_wait = max(max, max(bps_wait, iops_wait));

    Thanks.

    --
    tejun

    \
     
     \ /
      Last update: 2022-11-23 19:20    [W:3.159 / U:0.036 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site