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    SubjectRe: [PATCH 04/19] io-controller: Modify cfq to make use of flat elevator fair queuing
    Vivek Goyal wrote:
    > This patch changes cfq to use fair queuing code from elevator layer.
    >
    > Signed-off-by: Nauman Rafique <nauman@google.com>
    > Signed-off-by: Fabio Checconi <fabio@gandalf.sssup.it>
    > Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
    > Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
    > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
    > ---
    > block/Kconfig.iosched | 3 +-
    > block/cfq-iosched.c | 1097 +++++++++------------------------------------
    > include/linux/iocontext.h | 4 -
    > 3 files changed, 219 insertions(+), 885 deletions(-)
    >
    > diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
    > index 3398134..dd5224d 100644
    > --- a/block/Kconfig.iosched
    > +++ b/block/Kconfig.iosched
    > @@ -3,7 +3,7 @@ if BLOCK
    > menu "IO Schedulers"
    >
    > config ELV_FAIR_QUEUING
    > - bool "Elevator Fair Queuing Support"
    > + bool
    > default n
    > ---help---
    > Traditionally only cfq had notion of multiple queues and it did
    > @@ -46,6 +46,7 @@ config IOSCHED_DEADLINE
    >
    > config IOSCHED_CFQ
    > tristate "CFQ I/O scheduler"
    > + select ELV_FAIR_QUEUING
    > default y
    > ---help---
    > The CFQ I/O scheduler tries to distribute bandwidth equally
    > diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
    > index a55a9bd..f90c534 100644
    > --- a/block/cfq-iosched.c
    > +++ b/block/cfq-iosched.c
    > @@ -12,7 +12,6 @@
    > #include <linux/rbtree.h>
    > #include <linux/ioprio.h>
    > #include <linux/blktrace_api.h>
    > -
    > /*
    > * tunables
    > */
    > @@ -23,15 +22,7 @@ static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
    > 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_async_rq = 2;
    > -static int cfq_slice_idle = HZ / 125;
    > -
    > -/*
    > - * offset from end of service tree
    > - */
    > -#define CFQ_IDLE_DELAY (HZ / 5)
    >
    > /*
    > * below this threshold, we consider thinktime immediate
    > @@ -43,7 +34,7 @@ static int cfq_slice_idle = HZ / 125;
    >
    > #define RQ_CIC(rq) \
    > ((struct cfq_io_context *) (rq)->elevator_private)
    > -#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
    > +#define RQ_CFQQ(rq) (struct cfq_queue *) (ioq_sched_queue((rq)->ioq))
    >
    > static struct kmem_cache *cfq_pool;
    > static struct kmem_cache *cfq_ioc_pool;
    > @@ -53,8 +44,6 @@ static struct completion *ioc_gone;
    > static DEFINE_SPINLOCK(ioc_gone_lock);
    >
    > #define CFQ_PRIO_LISTS IOPRIO_BE_NR
    > -#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
    > -#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
    >
    > #define sample_valid(samples) ((samples) > 80)
    >
    > @@ -75,12 +64,6 @@ struct cfq_rb_root {
    > */
    > struct cfq_data {
    > struct request_queue *queue;
    > -
    > - /*
    > - * rr list of queues with requests and the count of them
    > - */
    > - struct cfq_rb_root service_tree;
    > -
    > /*
    > * Each priority tree is sorted by next_request position. These
    > * trees are used when determining if two or more queues are
    > @@ -88,39 +71,10 @@ struct cfq_data {
    > */
    > struct rb_root prio_trees[CFQ_PRIO_LISTS];
    >
    > - unsigned int busy_queues;
    > - /*
    > - * Used to track any pending rt requests so we can pre-empt current
    > - * non-RT cfqq in service when this value is non-zero.
    > - */
    > - unsigned int busy_rt_queues;
    > -
    > - int rq_in_driver;
    > int sync_flight;
    >
    > - /*
    > - * queue-depth detection
    > - */
    > - int rq_queued;
    > - int hw_tag;
    > - int hw_tag_samples;
    > - int rq_in_driver_peak;
    > -
    > - /*
    > - * idle window management
    > - */
    > - struct timer_list idle_slice_timer;
    > - struct work_struct unplug_work;
    > -
    > - struct cfq_queue *active_queue;
    > struct cfq_io_context *active_cic;
    >
    > - /*
    > - * async queue for each priority case
    > - */
    > - struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
    > - struct cfq_queue *async_idle_cfqq;
    > -
    > sector_t last_position;
    > unsigned long last_end_request;
    >
    > @@ -131,9 +85,7 @@ struct cfq_data {
    > unsigned int cfq_fifo_expire[2];
    > unsigned int cfq_back_penalty;
    > unsigned int cfq_back_max;
    > - unsigned int cfq_slice[2];
    > unsigned int cfq_slice_async_rq;
    > - unsigned int cfq_slice_idle;
    >
    > struct list_head cic_list;
    > };
    > @@ -142,16 +94,11 @@ struct cfq_data {
    > * Per process-grouping structure
    > */
    > struct cfq_queue {
    > - /* reference count */
    > - atomic_t ref;
    > + struct io_queue *ioq;
    > /* various state flags, see below */
    > unsigned int flags;
    > /* parent cfq_data */
    > struct cfq_data *cfqd;
    > - /* service_tree member */
    > - struct rb_node rb_node;
    > - /* service_tree key */
    > - unsigned long rb_key;
    > /* prio tree member */
    > struct rb_node p_node;
    > /* prio tree root we belong to, if any */
    > @@ -167,33 +114,23 @@ struct cfq_queue {
    > /* fifo list of requests in sort_list */
    > struct list_head fifo;
    >
    > - unsigned long slice_end;
    > - long slice_resid;
    > unsigned int slice_dispatch;
    >
    > /* pending metadata requests */
    > int meta_pending;
    > - /* number of requests that are on the dispatch list or inside driver */
    > - int dispatched;
    >
    > /* io prio of this group */
    > - unsigned short ioprio, org_ioprio;
    > - unsigned short ioprio_class, org_ioprio_class;
    > + unsigned short org_ioprio;
    > + unsigned short org_ioprio_class;
    >
    > pid_t pid;
    > };
    >
    > enum cfqq_state_flags {
    > - CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
    > - CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
    > - CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
    > CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
    > CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
    > CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
    > - CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
    > CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
    > - CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
    > - CFQ_CFQQ_FLAG_sync, /* synchronous queue */
    > CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
    > };
    >
    > @@ -211,16 +148,10 @@ static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
    > return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
    > }
    >
    > -CFQ_CFQQ_FNS(on_rr);
    > -CFQ_CFQQ_FNS(wait_request);
    > -CFQ_CFQQ_FNS(must_dispatch);
    > CFQ_CFQQ_FNS(must_alloc);
    > CFQ_CFQQ_FNS(must_alloc_slice);
    > CFQ_CFQQ_FNS(fifo_expire);
    > -CFQ_CFQQ_FNS(idle_window);
    > CFQ_CFQQ_FNS(prio_changed);
    > -CFQ_CFQQ_FNS(slice_new);
    > -CFQ_CFQQ_FNS(sync);
    > CFQ_CFQQ_FNS(coop);
    > #undef CFQ_CFQQ_FNS
    >
    > @@ -259,66 +190,32 @@ static inline int cfq_bio_sync(struct bio *bio)
    > return 0;
    > }
    >
    > -/*
    > - * scheduler run of queue, if there are requests pending and no one in the
    > - * driver that will restart queueing
    > - */
    > -static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
    > +static inline struct io_group *cfqq_to_io_group(struct cfq_queue *cfqq)
    > {
    > - if (cfqd->busy_queues) {
    > - cfq_log(cfqd, "schedule dispatch");
    > - kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
    > - }
    > + return ioq_to_io_group(cfqq->ioq);
    > }
    >
    > -static int cfq_queue_empty(struct request_queue *q)
    > +static inline int cfq_class_idle(struct cfq_queue *cfqq)
    > {
    > - struct cfq_data *cfqd = q->elevator->elevator_data;
    > -
    > - return !cfqd->busy_queues;
    > + return elv_ioq_class_idle(cfqq->ioq);
    > }
    >
    > -/*
    > - * Scale schedule slice based on io priority. Use the sync time slice only
    > - * if a queue is marked sync and has sync io queued. A sync queue with async
    > - * io only, should not get full sync slice length.
    > - */
    > -static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
    > - unsigned short prio)
    > -{
    > - const int base_slice = cfqd->cfq_slice[sync];
    > -
    > - WARN_ON(prio >= IOPRIO_BE_NR);
    > -
    > - return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
    > -}
    > -
    > -static inline int
    > -cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
    > +static inline int cfq_class_rt(struct cfq_queue *cfqq)
    > {
    > - return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
    > + return elv_ioq_class_rt(cfqq->ioq);
    > }

    Hi Vivek,

    cfq_class_rt isn't needed now, clean it up.

    Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
    ---
    block/cfq-iosched.c | 5 -----
    1 files changed, 0 insertions(+), 5 deletions(-)

    diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
    index 705e7ba..23b24b9 100644
    --- a/block/cfq-iosched.c
    +++ b/block/cfq-iosched.c
    @@ -234,11 +234,6 @@ static inline int cfq_class_idle(struct cfq_queue *cfqq)
    return elv_ioq_class_idle(cfqq->ioq);
    }

    -static inline int cfq_class_rt(struct cfq_queue *cfqq)
    -{
    - return elv_ioq_class_rt(cfqq->ioq);
    -}
    -
    static inline int cfq_cfqq_sync(struct cfq_queue *cfqq)
    {
    return elv_ioq_sync(cfqq->ioq);
    --
    1.5.4.rc3



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