Hi Jan,

Jens Axboe <ax...@kernel.dk> writes:

> On 11/16/2015 08:11 AM, Jan Kara wrote:
>> Hello,
>>
>> lately I was looking into a big performance hit we take when blkio
>> controller is enabled and jbd2 thread ends up in a different cgroup than
>> user process. E.g. dbench4 throughput drops from ~140 MB/s to ~20 MB/s.
>> However artificial dbench4 is, this kind of drop will likely be clearly
>> visible in real life workloads as well. With unified cgroup hierarchy
>> the above cgroup split between jbd2 and user processes is unavoidable
>> once you enable blkio controller so IMO we should accomodate that better.

Is group idle enabled?  What happens if you set that to 0?  What's the
storage?

>> I have couple of CFQ idling improvements / fixes which I'll post later this
>> week once I'll complete some round of benchmarking. They improve the
>> throughput to ~40 MB/s which helps but clearly there's still a big room for
>> improvement. The reason for the performance drop is essentially in idling
>> we do to avoid starvation of CFQ queues. Now when idling in this context,
>> current default of 8 ms idle window is far to large - we start the timer
>> after the final request is completed and thus we effectively give the
>> process 8 ms of CPU time to submit the next IO request. Which I think is
>> usually far too much.

I think I'd need to see blktrace data to make any real sense of this
problem statement.  It's just too vague.

>>                       The problem is that more fine grained idling is
>> actually problematic because e.g. SUSE distro kernels have HZ=250 and thus
>> 1 jiffy is 4 ms. Hence my proposal: Do you think it would be OK to convert
>> CFQ to use highres timers and do all the accounting in microseconds?
>> Then we could tune the idle time to be say 1ms or even autotune it based on
>> process' think time both of which I expect would get us much closer to
>> original throughput (4 ms idle window gets us to ~70 MB/s with my patches,
>> disabling idling gets us to original throughput as expected).
>
> Converting to a non-jiffies timer base should be quite fine. We didn't
> have hrtimers when CFQ was written :-)

I actually have a patch that allows setting slices at the usec
granularity, but didn't go so far as to use hrtimers.  I have no idea
why I wrote it, or whether it works.  ;-) I've attached it in case it's
useful to you, Jan.

Cheers,
Jeff

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 5da8e6e..fc50fa77 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -10,7 +10,7 @@
 #include <linux/slab.h>
 #include <linux/blkdev.h>
 #include <linux/elevator.h>
-#include <linux/jiffies.h>
+#include <linux/ktime.h>
 #include <linux/rbtree.h>
 #include <linux/ioprio.h>
 #include <linux/blktrace_api.h>
@@ -22,23 +22,23 @@
  */
 /* max queue in one round of service */
 static const int cfq_quantum = 8;
-static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
+static const int cfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
 /* maximum backwards seek, in KiB */
 static const int cfq_back_max = 16 * 1024;
 /* penalty of a backwards seek */
 static const int cfq_back_penalty = 2;
-static const int cfq_slice_sync = HZ / 10;
-static int cfq_slice_async = HZ / 25;
+static const int cfq_slice_sync = NSEC_PER_SEC / 10;
+static int cfq_slice_async = NSEC_PER_SEC / 25;
 static const int cfq_slice_async_rq = 2;
-static int cfq_slice_idle = HZ / 125;
-static int cfq_group_idle = HZ / 125;
-static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
+static int cfq_slice_idle = NSEC_PER_SEC / 125;
+static int cfq_group_idle = NSEC_PER_SEC / 125;
+static const int cfq_target_latency = NSEC_PER_SEC * 3/10; /* 300 ms */
 static const int cfq_hist_divisor = 4;
 
 /*
  * offset from end of service tree
  */
-#define CFQ_IDLE_DELAY         (HZ / 5)
+#define CFQ_IDLE_DELAY         (NSEC_PER_SEC / 5)
 
 /*
  * below this threshold, we consider thinktime immediate
@@ -89,7 +89,7 @@ struct cfq_rb_root {
        struct cfq_ttime ttime;
 };
 #define CFQ_RB_ROOT    (struct cfq_rb_root) { .rb = RB_ROOT, \
-                       .ttime = {.last_end_request = jiffies,},}
+                       .ttime = {.last_end_request = ktime_get_ns(),},}
 
 /*
  * Per process-grouping structure
@@ -104,7 +104,7 @@ struct cfq_queue {
        /* service_tree member */
        struct rb_node rb_node;
        /* service_tree key */
-       unsigned long rb_key;
+       u64 rb_key;
        /* prio tree member */
        struct rb_node p_node;
        /* prio tree root we belong to, if any */
@@ -125,8 +125,8 @@ struct cfq_queue {
        unsigned int allocated_slice;
        unsigned int slice_dispatch;
        /* time when first request from queue completed and slice started. */
-       unsigned long slice_start;
-       unsigned long slice_end;
+       u64 slice_start;
+       u64 slice_end;
        long slice_resid;
 
        /* pending priority requests */
@@ -1046,11 +1046,12 @@ static inline void
 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
        unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
+       u64 now = ktime_get_ns();
 
-       cfqq->slice_start = jiffies;
-       cfqq->slice_end = jiffies + slice;
+       cfqq->slice_start = now;
+       cfqq->slice_end = now + slice;
        cfqq->allocated_slice = slice;
-       cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
+       cfq_log_cfqq(cfqd, cfqq, "set_slice=%llu", cfqq->slice_end - now);
 }
 
 /*
@@ -1062,7 +1063,7 @@ static inline bool cfq_slice_used(struct cfq_queue *cfqq)
 {
        if (cfq_cfqq_slice_new(cfqq))
                return false;
-       if (time_before(jiffies, cfqq->slice_end))
+       if (ktime_get_ns() < cfqq->slice_end)
                return false;
 
        return true;
@@ -1426,27 +1427,27 @@ static inline unsigned int cfq_cfqq_slice_usage(struct 
cfq_queue *cfqq,
                                                unsigned int *unaccounted_time)
 {
        unsigned int slice_used;
+       u64 now = ktime_get_ns();
 
        /*
         * Queue got expired before even a single request completed or
         * got expired immediately after first request completion.
         */
-       if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
+       if (!cfqq->slice_start || cfqq->slice_start == now) {
                /*
                 * Also charge the seek time incurred to the group, otherwise
                 * if there are mutiple queues in the group, each can dispatch
                 * a single request on seeky media and cause lots of seek time
                 * and group will never know it.
                 */
-               slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
-                                       1);
+               slice_used = max_t(unsigned, (now - cfqq->dispatch_start), 1);
        } else {
-               slice_used = jiffies - cfqq->slice_start;
+               slice_used = now - cfqq->slice_start;
                if (slice_used > cfqq->allocated_slice) {
                        *unaccounted_time = slice_used - cfqq->allocated_slice;
                        slice_used = cfqq->allocated_slice;
                }
-               if (time_after(cfqq->slice_start, cfqq->dispatch_start))
+               if (cfqq->slice_start > cfqq->dispatch_start)
                        *unaccounted_time += cfqq->slice_start -
                                        cfqq->dispatch_start;
        }
@@ -1462,6 +1463,7 @@ static void cfq_group_served(struct cfq_data *cfqd, 
struct cfq_group *cfqg,
        int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
                        - cfqg->service_tree_idle.count;
        unsigned int vfr;
+       u64 now = ktime_get_ns();
 
        BUG_ON(nr_sync < 0);
        used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
@@ -1483,9 +1485,8 @@ static void cfq_group_served(struct cfq_data *cfqd, 
struct cfq_group *cfqg,
        cfq_group_service_tree_add(st, cfqg);
 
        /* This group is being expired. Save the context */
-       if (time_after(cfqd->workload_expires, jiffies)) {
-               cfqg->saved_wl_slice = cfqd->workload_expires
-                                               - jiffies;
+       if (cfqd->workload_expires > now) {
+               cfqg->saved_wl_slice = cfqd->workload_expires - now;
                cfqg->saved_wl_type = cfqd->serving_wl_type;
                cfqg->saved_wl_class = cfqd->serving_wl_class;
        } else
@@ -1517,7 +1518,7 @@ static void cfq_init_cfqg_base(struct cfq_group *cfqg)
                *st = CFQ_RB_ROOT;
        RB_CLEAR_NODE(&cfqg->rb_node);
 
-       cfqg->ttime.last_end_request = jiffies;
+       cfqg->ttime.last_end_request = ktime_get_ns();
 }
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
@@ -2024,10 +2025,11 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, 
struct cfq_queue *cfqq,
 {
        struct rb_node **p, *parent;
        struct cfq_queue *__cfqq;
-       unsigned long rb_key;
+       u64 rb_key;
        struct cfq_rb_root *st;
        int left;
        int new_cfqq = 1;
+       u64 now = ktime_get_ns();
 
        st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
        if (cfq_class_idle(cfqq)) {
@@ -2037,7 +2039,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, 
struct cfq_queue *cfqq,
                        __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
                        rb_key += __cfqq->rb_key;
                } else
-                       rb_key += jiffies;
+                       rb_key += now;
        } else if (!add_front) {
                /*
                 * Get our rb key offset. Subtract any residual slice
@@ -2045,13 +2047,13 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, 
struct cfq_queue *cfqq,
                 * count indicates slice overrun, and this should position
                 * the next service time further away in the tree.
                 */
-               rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
+               rb_key = cfq_slice_offset(cfqd, cfqq) + now;
                rb_key -= cfqq->slice_resid;
                cfqq->slice_resid = 0;
        } else {
-               rb_key = -HZ;
+               rb_key = -NSEC_PER_SEC;
                __cfqq = cfq_rb_first(st);
-               rb_key += __cfqq ? __cfqq->rb_key : jiffies;
+               rb_key += __cfqq ? __cfqq->rb_key : now;
        }
 
        if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
@@ -2077,7 +2079,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, 
struct cfq_queue *cfqq,
                /*
                 * sort by key, that represents service time.
                 */
-               if (time_before(rb_key, __cfqq->rb_key))
+               if (rb_key < __cfqq->rb_key)
                        p = &parent->rb_left;
                else {
                        p = &parent->rb_right;
@@ -2377,7 +2379,7 @@ cfq_merged_requests(struct request_queue *q, struct 
request *rq,
         * reposition in fifo if next is older than rq
         */
        if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
-           time_before(next->fifo_time, rq->fifo_time) &&
+           next->fifo_time < rq->fifo_time &&
            cfqq == RQ_CFQQ(next)) {
                list_move(&rq->queuelist, &next->queuelist);
                rq->fifo_time = next->fifo_time;
@@ -2438,7 +2440,7 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
                                cfqd->serving_wl_class, cfqd->serving_wl_type);
                cfqg_stats_update_avg_queue_size(cfqq->cfqg);
                cfqq->slice_start = 0;
-               cfqq->dispatch_start = jiffies;
+               cfqq->dispatch_start = ktime_get_ns();
                cfqq->allocated_slice = 0;
                cfqq->slice_end = 0;
                cfqq->slice_dispatch = 0;
@@ -2487,7 +2489,7 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct 
cfq_queue *cfqq,
                if (cfq_cfqq_slice_new(cfqq))
                        cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
                else
-                       cfqq->slice_resid = cfqq->slice_end - jiffies;
+                       cfqq->slice_resid = cfqq->slice_end - ktime_get_ns();
                cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
        }
 
@@ -2722,6 +2724,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
        struct cfq_queue *cfqq = cfqd->active_queue;
        struct cfq_io_cq *cic;
        unsigned long sl, group_idle = 0;
+       u64 now = ktime_get_ns();
 
        /*
         * SSD device without seek penalty, disable idling. But only do so
@@ -2764,7 +2767,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
         * time slice.
         */
        if (sample_valid(cic->ttime.ttime_samples) &&
-           (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
+           (cfqq->slice_end - now < cic->ttime.ttime_mean)) {
                cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
                             cic->ttime.ttime_mean);
                return;
@@ -2781,7 +2784,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
        else
                sl = cfqd->cfq_slice_idle;
 
-       mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
+       mod_timer(&cfqd->idle_slice_timer, now + sl);
        cfqg_stats_set_start_idle_time(cfqq->cfqg);
        cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
                        group_idle ? 1 : 0);
@@ -2824,7 +2827,7 @@ static struct request *cfq_check_fifo(struct cfq_queue 
*cfqq)
                return NULL;
 
        rq = rq_entry_fifo(cfqq->fifo.next);
-       if (time_before(jiffies, rq->fifo_time))
+       if (ktime_get_ns() < rq->fifo_time)
                rq = NULL;
 
        cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
@@ -2909,7 +2912,7 @@ static enum wl_type_t cfq_choose_wl_type(struct cfq_data 
*cfqd,
                /* select the one with lowest rb_key */
                queue = cfq_rb_first(st_for(cfqg, wl_class, i));
                if (queue &&
-                   (!key_valid || time_before(queue->rb_key, lowest_key))) {
+                   (!key_valid || queue->rb_key < lowest_key)) {
                        lowest_key = queue->rb_key;
                        cur_best = i;
                        key_valid = true;
@@ -2927,6 +2930,7 @@ choose_wl_class_and_type(struct cfq_data *cfqd, struct 
cfq_group *cfqg)
        struct cfq_rb_root *st;
        unsigned group_slice;
        enum wl_class_t original_class = cfqd->serving_wl_class;
+       u64 now = ktime_get_ns();
 
        /* Choose next priority. RT > BE > IDLE */
        if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
@@ -2935,7 +2939,7 @@ choose_wl_class_and_type(struct cfq_data *cfqd, struct 
cfq_group *cfqg)
                cfqd->serving_wl_class = BE_WORKLOAD;
        else {
                cfqd->serving_wl_class = IDLE_WORKLOAD;
-               cfqd->workload_expires = jiffies + 1;
+               cfqd->workload_expires = now + jiffies_to_nsecs(1);
                return;
        }
 
@@ -2953,7 +2957,7 @@ choose_wl_class_and_type(struct cfq_data *cfqd, struct 
cfq_group *cfqg)
        /*
         * check workload expiration, and that we still have other queues ready
         */
-       if (count && !time_after(jiffies, cfqd->workload_expires))
+       if (count && !(now > cfqd->workload_expires))
                return;
 
 new_workload:
@@ -2999,7 +3003,7 @@ new_workload:
 
        slice = max_t(unsigned, slice, CFQ_MIN_TT);
        cfq_log(cfqd, "workload slice:%d", slice);
-       cfqd->workload_expires = jiffies + slice;
+       cfqd->workload_expires = now + slice;
 }
 
 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
@@ -3017,16 +3021,17 @@ static struct cfq_group *cfq_get_next_cfqg(struct 
cfq_data *cfqd)
 static void cfq_choose_cfqg(struct cfq_data *cfqd)
 {
        struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
+       u64 now = ktime_get_ns();
 
        cfqd->serving_group = cfqg;
 
        /* Restore the workload type data */
        if (cfqg->saved_wl_slice) {
-               cfqd->workload_expires = jiffies + cfqg->saved_wl_slice;
+               cfqd->workload_expires = now + cfqg->saved_wl_slice;
                cfqd->serving_wl_type = cfqg->saved_wl_type;
                cfqd->serving_wl_class = cfqg->saved_wl_class;
        } else
-               cfqd->workload_expires = jiffies - 1;
+               cfqd->workload_expires = now - 1;
 
        choose_wl_class_and_type(cfqd, cfqg);
 }
@@ -3038,6 +3043,7 @@ static void cfq_choose_cfqg(struct cfq_data *cfqd)
 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 {
        struct cfq_queue *cfqq, *new_cfqq = NULL;
+       u64 now = ktime_get_ns();
 
        cfqq = cfqd->active_queue;
        if (!cfqq)
@@ -3109,7 +3115,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data 
*cfqd)
         **/
        if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
            (cfq_cfqq_slice_new(cfqq) ||
-           (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
+           (cfqq->slice_end - now > now - cfqq->slice_start))) {
                cfq_clear_cfqq_deep(cfqq);
                cfq_clear_cfqq_idle_window(cfqq);
        }
@@ -3187,11 +3193,12 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd)
 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
        struct cfq_queue *cfqq)
 {
+       u64 now = ktime_get_ns();
+
        /* the queue hasn't finished any request, can't estimate */
        if (cfq_cfqq_slice_new(cfqq))
                return true;
-       if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
-               cfqq->slice_end))
+       if (now + cfqd->cfq_slice_idle * cfqq->dispatched > cfqq->slice_end)
                return true;
 
        return false;
@@ -3266,7 +3273,7 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, 
struct cfq_queue *cfqq)
         * based on the last sync IO we serviced
         */
        if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
-               unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
+               unsigned long last_sync = ktime_get_ns() - 
cfqd->last_delayed_sync;
                unsigned int depth;
 
                depth = last_sync / cfqd->cfq_slice[1];
@@ -3352,7 +3359,7 @@ static int cfq_dispatch_requests(struct request_queue *q, 
int force)
        if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
            cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
            cfq_class_idle(cfqq))) {
-               cfqq->slice_end = jiffies + 1;
+               cfqq->slice_end = ktime_get_ns() + 1;
                cfq_slice_expired(cfqd, 0);
        }
 
@@ -3430,7 +3437,7 @@ static void cfq_init_icq(struct io_cq *icq)
 {
        struct cfq_io_cq *cic = icq_to_cic(icq);
 
-       cic->ttime.last_end_request = jiffies;
+       cic->ttime.last_end_request = ktime_get_ns();
 }
 
 static void cfq_exit_icq(struct io_cq *icq)
@@ -3694,7 +3701,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct 
cfq_io_cq *cic,
 static void
 __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
 {
-       unsigned long elapsed = jiffies - ttime->last_end_request;
+       unsigned long elapsed = ktime_get_ns() - ttime->last_end_request;
        elapsed = min(elapsed, 2UL * slice_idle);
 
        ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
@@ -3947,7 +3954,7 @@ static void cfq_insert_request(struct request_queue *q, 
struct request *rq)
        cfq_log_cfqq(cfqd, cfqq, "insert_request");
        cfq_init_prio_data(cfqq, RQ_CIC(rq));
 
-       rq->fifo_time = jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
+       rq->fifo_time = ktime_get_ns() + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
        list_add_tail(&rq->queuelist, &cfqq->fifo);
        cfq_add_rq_rb(rq);
        cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
@@ -3995,6 +4002,7 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd)
 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
        struct cfq_io_cq *cic = cfqd->active_cic;
+       u64 now = ktime_get_ns();
 
        /* If the queue already has requests, don't wait */
        if (!RB_EMPTY_ROOT(&cfqq->sort_list))
@@ -4013,7 +4021,7 @@ static bool cfq_should_wait_busy(struct cfq_data *cfqd, 
struct cfq_queue *cfqq)
 
        /* if slice left is less than think time, wait busy */
        if (cic && sample_valid(cic->ttime.ttime_samples)
-           && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
+           && (cfqq->slice_end - now < cic->ttime.ttime_mean))
                return true;
 
        /*
@@ -4023,7 +4031,7 @@ static bool cfq_should_wait_busy(struct cfq_data *cfqd, 
struct cfq_queue *cfqq)
         * case where think time is less than a jiffy, mark the queue wait
         * busy if only 1 jiffy is left in the slice.
         */
-       if (cfqq->slice_end - jiffies == 1)
+       if (cfqq->slice_end - now <= jiffies_to_nsecs(1))
                return true;
 
        return false;
@@ -4034,9 +4042,8 @@ static void cfq_completed_request(struct request_queue 
*q, struct request *rq)
        struct cfq_queue *cfqq = RQ_CFQQ(rq);
        struct cfq_data *cfqd = cfqq->cfqd;
        const int sync = rq_is_sync(rq);
-       unsigned long now;
+       u64 now = ktime_get_ns();
 
-       now = jiffies;
        cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
                     !!(rq->cmd_flags & REQ_NOIDLE));
 
@@ -4064,7 +4071,7 @@ static void cfq_completed_request(struct request_queue 
*q, struct request *rq)
                                        cfqq_type(cfqq));
 
                st->ttime.last_end_request = now;
-               if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
+               if (!(rq->start_time + cfqd->cfq_fifo_expire[1] > now))
                        cfqd->last_delayed_sync = now;
        }
 
@@ -4092,7 +4099,7 @@ static void cfq_completed_request(struct request_queue 
*q, struct request *rq)
                        unsigned long extend_sl = cfqd->cfq_slice_idle;
                        if (!cfqd->cfq_slice_idle)
                                extend_sl = cfqd->cfq_group_idle;
-                       cfqq->slice_end = jiffies + extend_sl;
+                       cfqq->slice_end = now + extend_sl;
                        cfq_mark_cfqq_wait_busy(cfqq);
                        cfq_log_cfqq(cfqd, cfqq, "will busy wait");
                }
@@ -4468,7 +4475,7 @@ static int cfq_init_queue(struct request_queue *q, struct 
elevator_type *e)
         * we optimistically start assuming sync ops weren't delayed in last
         * second, in order to have larger depth for async operations.
         */
-       cfqd->last_delayed_sync = jiffies - HZ;
+       cfqd->last_delayed_sync = ktime_get_ns() - NSEC_PER_SEC;
        return 0;
 
 out_free:
@@ -4501,7 +4508,7 @@ static ssize_t __FUNC(struct elevator_queue *e, char 
*page)               \
        struct cfq_data *cfqd = e->elevator_data;                       \
        unsigned int __data = __VAR;                                    \
        if (__CONV)                                                     \
-               __data = jiffies_to_msecs(__data);                      \
+               __data = __data / NSEC_PER_MSEC;                        \
        return cfq_var_show(__data, (page));                            \
 }
 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
@@ -4518,6 +4525,20 @@ SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 
0);
 SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
 #undef SHOW_FUNCTION
 
+#define USEC_SHOW_FUNCTION(__FUNC, __VAR)                              \
+static ssize_t __FUNC(struct elevator_queue *e, char *page)            \
+{                                                                      \
+       struct cfq_data *cfqd = e->elevator_data;                       \
+       unsigned int __data = __VAR;                                    \
+       __data = __data / NSEC_PER_USEC;                                \
+       return cfq_var_show(__data, (page));                            \
+}
+USEC_SHOW_FUNCTION(cfq_slice_idle_us_show, cfqd->cfq_slice_idle);
+USEC_SHOW_FUNCTION(cfq_group_idle_us_show, cfqd->cfq_group_idle);
+USEC_SHOW_FUNCTION(cfq_slice_sync_us_show, cfqd->cfq_slice[1]);
+USEC_SHOW_FUNCTION(cfq_slice_async_us_show, cfqd->cfq_slice[0]);
+#undef USEC_SHOW_FUNCTION
+
 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                        
\
 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t 
count)        \
 {                                                                      \
@@ -4529,7 +4550,7 @@ static ssize_t __FUNC(struct elevator_queue *e, const 
char *page, size_t count)
        else if (__data > (MAX))                                        \
                __data = (MAX);                                         \
        if (__CONV)                                                     \
-               *(__PTR) = msecs_to_jiffies(__data);                    \
+               *(__PTR) = __data * NSEC_PER_MSEC;                      \
        else                                                            \
                *(__PTR) = __data;                                      \
        return ret;                                                     \
@@ -4552,6 +4573,25 @@ STORE_FUNCTION(cfq_low_latency_store, 
&cfqd->cfq_latency, 0, 1, 0);
 STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, 
UINT_MAX, 1);
 #undef STORE_FUNCTION
 
+#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX)                   \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t 
count)        \
+{                                                                      \
+       struct cfq_data *cfqd = e->elevator_data;                       \
+       unsigned int __data;                                            \
+       int ret = cfq_var_store(&__data, (page), count);                \
+       if (__data < (MIN))                                             \
+               __data = (MIN);                                         \
+       else if (__data > (MAX))                                        \
+               __data = (MAX);                                         \
+       *(__PTR) = __data * NSEC_PER_USEC;                              \
+       return ret;                                                     \
+}
+USEC_STORE_FUNCTION(cfq_slice_idle_us_store, &cfqd->cfq_slice_idle, 0, 
UINT_MAX);
+USEC_STORE_FUNCTION(cfq_group_idle_us_store, &cfqd->cfq_group_idle, 0, 
UINT_MAX);
+USEC_STORE_FUNCTION(cfq_slice_sync_us_store, &cfqd->cfq_slice[1], 1, UINT_MAX);
+USEC_STORE_FUNCTION(cfq_slice_async_us_store, &cfqd->cfq_slice[0], 1, 
UINT_MAX);
+#undef USEC_STORE_FUNCTION
+
 #define CFQ_ATTR(name) \
        __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
 
@@ -4562,10 +4602,14 @@ static struct elv_fs_entry cfq_attrs[] = {
        CFQ_ATTR(back_seek_max),
        CFQ_ATTR(back_seek_penalty),
        CFQ_ATTR(slice_sync),
+       CFQ_ATTR(slice_sync_us),
        CFQ_ATTR(slice_async),
+       CFQ_ATTR(slice_async_us),
        CFQ_ATTR(slice_async_rq),
        CFQ_ATTR(slice_idle),
+       CFQ_ATTR(slice_idle_us),
        CFQ_ATTR(group_idle),
+       CFQ_ATTR(group_idle_us),
        CFQ_ATTR(low_latency),
        CFQ_ATTR(target_latency),
        __ATTR_NULL
--
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