| Message ID | 20210608230703.19510-15-bvanassche@acm.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Improve I/O priority support | expand |
On 2021/06/09 8:07, Bart Van Assche wrote: > While one or more requests with a certain I/O priority are pending, do not > dispatch lower priority requests. Dispatch lower priority requests anyway > after the "aging" time has expired. > > This patch has been tested as follows: > > modprobe scsi_debug ndelay=1000000 max_queue=16 && > sd='' && > while [ -z "$sd" ]; do > sd=/dev/$(basename /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/*) > done && > echo $((100*1000)) > /sys/block/$sd/queue/iosched/aging_expire && > cd /sys/fs/cgroup/blkio/ && > echo $$ >cgroup.procs && > echo 2 >blkio.prio.class && > mkdir -p hipri && > cd hipri && > echo 1 >blkio.prio.class && > { max-iops -a1 -d32 -j1 -e mq-deadline $sd >& ~/low-pri.txt & } && > echo $$ >cgroup.procs && > max-iops -a1 -d32 -j1 -e mq-deadline $sd >& ~/hi-pri.txt > > Result: > * 11000 IOPS for the high-priority job > * 400 IOPS for the low-priority job > > If the aging expiry time is changed from 100s into 0, the IOPS results change > into 6712 and 6796 IOPS. > > The max-iops script is a script that runs fio with the following arguments: > --bs=4K --gtod_reduce=1 --ioengine=libaio --ioscheduler=${arg_e} --runtime=60 > --norandommap --rw=read --thread --buffered=0 --numjobs=${arg_j} > --iodepth=${arg_d} --iodepth_batch_submit=${arg_a} > --iodepth_batch_complete=$((arg_d / 2)) --name=${positional_argument_1} > --filename=${positional_argument_1} > > Cc: Damien Le Moal <damien.lemoal@wdc.com> > Cc: Hannes Reinecke <hare@suse.de> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Ming Lei <ming.lei@redhat.com> > Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com> > Cc: Himanshu Madhani <himanshu.madhani@oracle.com> > Signed-off-by: Bart Van Assche <bvanassche@acm.org> > --- > block/mq-deadline-main.c | 42 +++++++++++++++++++++++++++++++++++----- > 1 file changed, 37 insertions(+), 5 deletions(-) > > diff --git a/block/mq-deadline-main.c b/block/mq-deadline-main.c > index 1b2b6c1de5b8..cecdb475a610 100644 > --- a/block/mq-deadline-main.c > +++ b/block/mq-deadline-main.c > @@ -32,6 +32,11 @@ > */ > static const int read_expire = HZ / 2; /* max time before a read is submitted. */ > static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ > +/* > + * Time after which to dispatch lower priority requests even if higher > + * priority requests are pending. > + */ > +static const int aging_expire = 10 * HZ; > static const int writes_starved = 2; /* max times reads can starve a write */ > static const int fifo_batch = 16; /* # of sequential requests treated as one > by the above parameters. For throughput. */ > @@ -90,6 +95,7 @@ struct deadline_data { > int writes_starved; > int front_merges; > u32 async_depth; > + int aging_expire; > > spinlock_t lock; > spinlock_t zone_lock; > @@ -363,10 +369,10 @@ deadline_next_request(struct deadline_data *dd, enum dd_prio prio, > > /* > * deadline_dispatch_requests selects the best request according to > - * read/write expire, fifo_batch, etc > + * read/write expire, fifo_batch, etc and with a start time <= @latest. > */ > static struct request *__dd_dispatch_request(struct deadline_data *dd, > - enum dd_prio prio) > + enum dd_prio prio, u64 latest_start_ns) > { > struct request *rq, *next_rq; > enum dd_data_dir data_dir; > @@ -378,6 +384,8 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, > if (!list_empty(&dd->dispatch[prio])) { > rq = list_first_entry(&dd->dispatch[prio], struct request, > queuelist); > + if (rq->start_time_ns > latest_start_ns) > + return NULL; > list_del_init(&rq->queuelist); > goto done; > } > @@ -457,6 +465,8 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, > dd->batching = 0; > > dispatch_request: > + if (rq->start_time_ns > latest_start_ns) > + return NULL; > /* > * rq is the selected appropriate request. > */ > @@ -493,15 +503,32 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, > static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) > { > struct deadline_data *dd = hctx->queue->elevator->elevator_data; > - struct request *rq; > + const u64 now_ns = ktime_get_ns(); > + struct request *rq = NULL; > enum dd_prio prio; > > spin_lock(&dd->lock); > - for (prio = 0; prio <= DD_PRIO_MAX; prio++) { > - rq = __dd_dispatch_request(dd, prio); > + /* > + * Start with dispatching requests whose deadline expired more than > + * aging_expire jiffies ago. > + */ > + for (prio = DD_BE_PRIO; prio <= DD_PRIO_MAX; prio++) { > + rq = __dd_dispatch_request(dd, prio, now_ns - > + jiffies_to_nsecs(dd->aging_expire)); > if (rq) > + goto unlock; > + } > + /* > + * Next, dispatch requests in priority order. Ignore lower priority > + * requests if any higher priority requests are pending. > + */ > + for (prio = 0; prio <= DD_PRIO_MAX; prio++) { > + rq = __dd_dispatch_request(dd, prio, now_ns); > + if (rq || dd_queued(dd, prio)) > break; > } > + > +unlock: > spin_unlock(&dd->lock); > > return rq; > @@ -607,6 +634,7 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e) > dd->writes_starved = writes_starved; > dd->front_merges = 1; > dd->fifo_batch = fifo_batch; > + dd->aging_expire = aging_expire; > spin_lock_init(&dd->lock); > spin_lock_init(&dd->zone_lock); > > @@ -725,6 +753,7 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, > trace_block_rq_insert(rq); > > if (at_head) { > + rq->fifo_time = jiffies; > list_add(&rq->queuelist, &dd->dispatch[prio]); > } else { > deadline_add_rq_rb(dd, rq); > @@ -841,6 +870,7 @@ static ssize_t __FUNC(struct elevator_queue *e, char *page) \ > #define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR)) > SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]); > SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]); > +SHOW_JIFFIES(deadline_aging_expire_show, dd->aging_expire); > SHOW_INT(deadline_writes_starved_show, dd->writes_starved); > SHOW_INT(deadline_front_merges_show, dd->front_merges); > SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch); > @@ -869,6 +899,7 @@ static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) > STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies) > STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX); > STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX); > +STORE_JIFFIES(deadline_aging_expire_store, &dd->aging_expire, 0, INT_MAX); > STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX); > STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1); > STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX); > @@ -885,6 +916,7 @@ static struct elv_fs_entry deadline_attrs[] = { > DD_ATTR(writes_starved), > DD_ATTR(front_merges), > DD_ATTR(fifo_batch), > + DD_ATTR(aging_expire), > __ATTR_NULL > }; > > Looks good. Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
On 6/9/21 1:07 AM, Bart Van Assche wrote: > While one or more requests with a certain I/O priority are pending, do not > dispatch lower priority requests. Dispatch lower priority requests anyway > after the "aging" time has expired. > > This patch has been tested as follows: > > modprobe scsi_debug ndelay=1000000 max_queue=16 && > sd='' && > while [ -z "$sd" ]; do > sd=/dev/$(basename /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/*) > done && > echo $((100*1000)) > /sys/block/$sd/queue/iosched/aging_expire && > cd /sys/fs/cgroup/blkio/ && > echo $$ >cgroup.procs && > echo 2 >blkio.prio.class && > mkdir -p hipri && > cd hipri && > echo 1 >blkio.prio.class && > { max-iops -a1 -d32 -j1 -e mq-deadline $sd >& ~/low-pri.txt & } && > echo $$ >cgroup.procs && > max-iops -a1 -d32 -j1 -e mq-deadline $sd >& ~/hi-pri.txt > > Result: > * 11000 IOPS for the high-priority job > * 400 IOPS for the low-priority job > > If the aging expiry time is changed from 100s into 0, the IOPS results change > into 6712 and 6796 IOPS. > > The max-iops script is a script that runs fio with the following arguments: > --bs=4K --gtod_reduce=1 --ioengine=libaio --ioscheduler=${arg_e} --runtime=60 > --norandommap --rw=read --thread --buffered=0 --numjobs=${arg_j} > --iodepth=${arg_d} --iodepth_batch_submit=${arg_a} > --iodepth_batch_complete=$((arg_d / 2)) --name=${positional_argument_1} > --filename=${positional_argument_1} > > Cc: Damien Le Moal <damien.lemoal@wdc.com> > Cc: Hannes Reinecke <hare@suse.de> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Ming Lei <ming.lei@redhat.com> > Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com> > Cc: Himanshu Madhani <himanshu.madhani@oracle.com> > Signed-off-by: Bart Van Assche <bvanassche@acm.org> > --- > block/mq-deadline-main.c | 42 +++++++++++++++++++++++++++++++++++----- > 1 file changed, 37 insertions(+), 5 deletions(-) > Reviewed-by: Hannes Reinecke <hare@suse.de> Cheers, Hannes
diff --git a/block/mq-deadline-main.c b/block/mq-deadline-main.c index 1b2b6c1de5b8..cecdb475a610 100644 --- a/block/mq-deadline-main.c +++ b/block/mq-deadline-main.c @@ -32,6 +32,11 @@ */ static const int read_expire = HZ / 2; /* max time before a read is submitted. */ static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ +/* + * Time after which to dispatch lower priority requests even if higher + * priority requests are pending. + */ +static const int aging_expire = 10 * HZ; static const int writes_starved = 2; /* max times reads can starve a write */ static const int fifo_batch = 16; /* # of sequential requests treated as one by the above parameters. For throughput. */ @@ -90,6 +95,7 @@ struct deadline_data { int writes_starved; int front_merges; u32 async_depth; + int aging_expire; spinlock_t lock; spinlock_t zone_lock; @@ -363,10 +369,10 @@ deadline_next_request(struct deadline_data *dd, enum dd_prio prio, /* * deadline_dispatch_requests selects the best request according to - * read/write expire, fifo_batch, etc + * read/write expire, fifo_batch, etc and with a start time <= @latest. */ static struct request *__dd_dispatch_request(struct deadline_data *dd, - enum dd_prio prio) + enum dd_prio prio, u64 latest_start_ns) { struct request *rq, *next_rq; enum dd_data_dir data_dir; @@ -378,6 +384,8 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, if (!list_empty(&dd->dispatch[prio])) { rq = list_first_entry(&dd->dispatch[prio], struct request, queuelist); + if (rq->start_time_ns > latest_start_ns) + return NULL; list_del_init(&rq->queuelist); goto done; } @@ -457,6 +465,8 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, dd->batching = 0; dispatch_request: + if (rq->start_time_ns > latest_start_ns) + return NULL; /* * rq is the selected appropriate request. */ @@ -493,15 +503,32 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) { struct deadline_data *dd = hctx->queue->elevator->elevator_data; - struct request *rq; + const u64 now_ns = ktime_get_ns(); + struct request *rq = NULL; enum dd_prio prio; spin_lock(&dd->lock); - for (prio = 0; prio <= DD_PRIO_MAX; prio++) { - rq = __dd_dispatch_request(dd, prio); + /* + * Start with dispatching requests whose deadline expired more than + * aging_expire jiffies ago. + */ + for (prio = DD_BE_PRIO; prio <= DD_PRIO_MAX; prio++) { + rq = __dd_dispatch_request(dd, prio, now_ns - + jiffies_to_nsecs(dd->aging_expire)); if (rq) + goto unlock; + } + /* + * Next, dispatch requests in priority order. Ignore lower priority + * requests if any higher priority requests are pending. + */ + for (prio = 0; prio <= DD_PRIO_MAX; prio++) { + rq = __dd_dispatch_request(dd, prio, now_ns); + if (rq || dd_queued(dd, prio)) break; } + +unlock: spin_unlock(&dd->lock); return rq; @@ -607,6 +634,7 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e) dd->writes_starved = writes_starved; dd->front_merges = 1; dd->fifo_batch = fifo_batch; + dd->aging_expire = aging_expire; spin_lock_init(&dd->lock); spin_lock_init(&dd->zone_lock); @@ -725,6 +753,7 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, trace_block_rq_insert(rq); if (at_head) { + rq->fifo_time = jiffies; list_add(&rq->queuelist, &dd->dispatch[prio]); } else { deadline_add_rq_rb(dd, rq); @@ -841,6 +870,7 @@ static ssize_t __FUNC(struct elevator_queue *e, char *page) \ #define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR)) SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]); SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]); +SHOW_JIFFIES(deadline_aging_expire_show, dd->aging_expire); SHOW_INT(deadline_writes_starved_show, dd->writes_starved); SHOW_INT(deadline_front_merges_show, dd->front_merges); SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch); @@ -869,6 +899,7 @@ static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies) STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX); STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX); +STORE_JIFFIES(deadline_aging_expire_store, &dd->aging_expire, 0, INT_MAX); STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX); STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1); STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX); @@ -885,6 +916,7 @@ static struct elv_fs_entry deadline_attrs[] = { DD_ATTR(writes_starved), DD_ATTR(front_merges), DD_ATTR(fifo_batch), + DD_ATTR(aging_expire), __ATTR_NULL };
While one or more requests with a certain I/O priority are pending, do not dispatch lower priority requests. Dispatch lower priority requests anyway after the "aging" time has expired. This patch has been tested as follows: modprobe scsi_debug ndelay=1000000 max_queue=16 && sd='' && while [ -z "$sd" ]; do sd=/dev/$(basename /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/*) done && echo $((100*1000)) > /sys/block/$sd/queue/iosched/aging_expire && cd /sys/fs/cgroup/blkio/ && echo $$ >cgroup.procs && echo 2 >blkio.prio.class && mkdir -p hipri && cd hipri && echo 1 >blkio.prio.class && { max-iops -a1 -d32 -j1 -e mq-deadline $sd >& ~/low-pri.txt & } && echo $$ >cgroup.procs && max-iops -a1 -d32 -j1 -e mq-deadline $sd >& ~/hi-pri.txt Result: * 11000 IOPS for the high-priority job * 400 IOPS for the low-priority job If the aging expiry time is changed from 100s into 0, the IOPS results change into 6712 and 6796 IOPS. The max-iops script is a script that runs fio with the following arguments: --bs=4K --gtod_reduce=1 --ioengine=libaio --ioscheduler=${arg_e} --runtime=60 --norandommap --rw=read --thread --buffered=0 --numjobs=${arg_j} --iodepth=${arg_d} --iodepth_batch_submit=${arg_a} --iodepth_batch_complete=$((arg_d / 2)) --name=${positional_argument_1} --filename=${positional_argument_1} Cc: Damien Le Moal <damien.lemoal@wdc.com> Cc: Hannes Reinecke <hare@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com> Cc: Himanshu Madhani <himanshu.madhani@oracle.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- block/mq-deadline-main.c | 42 +++++++++++++++++++++++++++++++++++----- 1 file changed, 37 insertions(+), 5 deletions(-)