| Message ID | 20221017020011.25016-8-shikemeng@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | A few cleanup and bugfix patches for blk-iocost | expand |
On Mon, Oct 17, 2022 at 10:00:10AM +0800, Kemeng Shi wrote: > Some member of struct ioc_gq will not be accessed before it's > first activation and will be initialized again in it's first > activation after ioc_pd_init. To be more specific: > 1)Member iocg->vtime and iocg->done_vtime will set to target in > activation which only expects vtime is equal to done_vtime in > first activation. > 2)Member iocg->active_period will be set with ioc->cur_period > again in first activation. > > Remove the redundant initialization to improve ioc_pd_init a > littile bit. > > The parameter now of weight_updated will not be used if iocg is > not active, so pass NULL to weight_update here is safe and we > can remove call to ioc_now. This isn't a meaningful optimization and makes the code fragile for no practical gain. Let's not do this. Thanks.
diff --git a/block/blk-iocost.c b/block/blk-iocost.c index fa90f471dfdc..4815e676733d 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -2946,16 +2946,10 @@ static void ioc_pd_init(struct blkg_policy_data *pd) struct ioc_gq *iocg = pd_to_iocg(pd); struct blkcg_gq *blkg = pd_to_blkg(&iocg->pd); struct ioc *ioc = q_to_ioc(blkg->q); - struct ioc_now now; struct blkcg_gq *tblkg; unsigned long flags; - ioc_now(ioc, &now); - iocg->ioc = ioc; - atomic64_set(&iocg->vtime, now.vnow); - atomic64_set(&iocg->done_vtime, now.vnow); - atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period)); INIT_LIST_HEAD(&iocg->active_list); INIT_LIST_HEAD(&iocg->walk_list); INIT_LIST_HEAD(&iocg->surplus_list); @@ -2974,7 +2968,7 @@ static void ioc_pd_init(struct blkg_policy_data *pd) } spin_lock_irqsave(&ioc->lock, flags); - weight_updated(iocg, &now); + weight_updated(iocg, NULL); spin_unlock_irqrestore(&ioc->lock, flags); }
Some member of struct ioc_gq will not be accessed before it's first activation and will be initialized again in it's first activation after ioc_pd_init. To be more specific: 1)Member iocg->vtime and iocg->done_vtime will set to target in activation which only expects vtime is equal to done_vtime in first activation. 2)Member iocg->active_period will be set with ioc->cur_period again in first activation. Remove the redundant initialization to improve ioc_pd_init a littile bit. The parameter now of weight_updated will not be used if iocg is not active, so pass NULL to weight_update here is safe and we can remove call to ioc_now. Signed-off-by: Kemeng Shi <shikemeng@huawei.com> --- block/blk-iocost.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)