Messages in this thread | | | Date | Fri, 11 Jan 2013 15:26:37 +0100 | From | Jens Axboe <> | Subject | Re: [PATCH] blkcg: Before starting a new slice, firstly count bps/iops limit in func tg_may_dispatch. |
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On 2013-01-11 10:11, majianpeng wrote: > In func tg_may_dispatch, >> if (throtl_slice_used(td, tg, rw)) >> throtl_start_new_slice(td, tg, rw); > ... >> if (tg_with_in_bps_limit(td, tg, bio, &bps_wait) >> && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) { > > In funcs tg_with_in_(bps/iops)_limit, it used the slice_start to count. > So if privious slice expired, it start a new slice.This can cause hung > task. > > The next steps can repeat this bug. > 1:echo "8:48 10240" > blkio.throttle.write_bps_devic > 2:dd if=/dev/zero of=/dev/sdd bs=1M count=1 oflag=direct > > Using the blktrace, the messages about throttle: > root@kernel:/mnt/programs# blktrace -d /dev/sdd -a notify -o -|blkparse -i - > 8,48 1 0 0.000000000 0 m N throtl / [W] new slice start=4294854679 end=4294854779 jiffies=4294854679 > 8,48 1 0 0.000000966 0 m N throtl / [W] extend slice start=4294854679 end=4294905900 jiffies=4294854679 > 8,48 1 0 0.000002553 0 m N throtl / [W] bio. bdisp=0 sz=524288 bps=10240 iodisp=0 iops=4294967295 queued=0/0 > 8,48 1 0 0.000004788 0 m N throtl schedule work. delay=51200 jiffies=4294854679 > 8,48 1 0 51.304698681 0 m N throtl dispatch nr_queued=1 read=0 write=1 > 8,48 1 0 51.304701979 0 m N throtl / [W] new slice start=4294905984 end=4294906084 jiffies=4294905984 > 8,48 1 0 51.304703329 0 m N throtl / [W] extend slice start=4294905984 end=4294957200 jiffies=4294905984 > 8,48 1 0 51.304705783 0 m N throtl schedule work. delay=51200 jiffies=4294905984 > 8,48 1 0 102.632697082 0 m N throtl dispatch nr_queued=1 read=0 write=1 > 8,48 1 0 102.632700544 0 m N throtl / [W] new slice start=4294957312 end=4294957412 jiffies=4294957312 > 8,48 1 0 102.632701922 0 m N throtl / [W] extend slice start=4294957312 end=4295008600 jiffies=4294957312 > 8,48 1 0 102.632704016 0 m N throtl schedule work. delay=51200 jiffies=4294957312 > 8,48 1 0 153.960696503 0 m N throtl dispatch nr_queued=1 read=0 write=1 > 8,48 1 0 153.960699797 0 m N throtl / [W] new slice start=4295008640 end=4295008740 jiffies=4295008640 > 8,48 1 0 153.960701153 0 m N throtl / [W] extend slice start=4295008640 end=4295059900 jiffies=4295008640 > 8,48 1 0 153.960703218 0 m N throtl schedule work. delay=51200 jiffies=4295008640 > 8,48 1 0 205.288697067 0 m N throtl dispatch nr_queued=1 read=0 write=1 > 8,48 1 0 205.288700268 0 m N throtl / [W] new slice start=4295059968 end=4295060068 jiffies=4295059968 > 8,48 1 0 205.288701630 0 m N throtl / [W] extend slice start=4295059968 end=4295111200 jiffies=4295059968 > 8,48 1 0 205.288703784 0 m N throtl schedule work. delay=51200 jiffies=4295059968 > 8,48 1 0 256.616696184 0 m N throtl dispatch nr_queued=1 read=0 write=1 > 8,48 1 0 256.616699266 0 m N throtl / [W] new slice start=4295111296 end=4295111396 jiffies=4295111296 > 8,48 1 0 256.616700574 0 m N throtl / [W] extend slice start=4295111296 end=4295162500 jiffies=4295111296 > 8,48 1 0 256.616702701 0 m N throtl schedule work. delay=51200 jiffies=4295111296 > > Signed-off-by: Jianpeng Ma <majianpeng@gmail.com> > --- > block/blk-throttle.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/block/blk-throttle.c b/block/blk-throttle.c > index 3114622..9258789 100644 > --- a/block/blk-throttle.c > +++ b/block/blk-throttle.c > @@ -645,6 +645,15 @@ static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg, > } > > /* > + * If privious slice expired,then start new slice. > + * But counting bps and iops limit need privious slice info > + * which ->slice_start. > + */ > + if (tg_with_in_bps_limit(td, tg, bio, &bps_wait) > + && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) > + if (wait) > + *wait = 0; > + /* > * If previous slice expired, start a new one otherwise renew/extend > * existing slice to make sure it is at least throtl_slice interval > * long since now. > @@ -656,12 +665,8 @@ static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg, > throtl_extend_slice(td, tg, rw, jiffies + throtl_slice); > } > > - if (tg_with_in_bps_limit(td, tg, bio, &bps_wait) > - && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) { > - if (wait) > - *wait = 0; > + if (!(bps_wait || iops_wait)) > return 1; > - } > > max_wait = max(bps_wait, iops_wait);
Looks pretty sane to me. Vivek?
-- Jens Axboe
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