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Subject[patch v2 4/8]block: fiops add ioprio support
Add CFQ-like ioprio support. Priority A will get 20% more share than priority
A+1, which matches CFQ.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
---
block/fiops-iosched.c | 103 ++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 92 insertions(+), 11 deletions(-)

Index: linux/block/fiops-iosched.c
===================================================================
--- linux.orig/block/fiops-iosched.c 2012-01-18 14:42:18.000000000 +0800
+++ linux/block/fiops-iosched.c 2012-01-18 14:43:51.000000000 +0800
@@ -20,6 +20,8 @@
#define VIOS_SYNC_SCALE (2)
#define VIOS_ASYNC_SCALE (5)

+#define VIOS_PRIO_SCALE (5)
+
struct fiops_rb_root {
struct rb_root rb;
struct rb_node *left;
@@ -29,10 +31,17 @@ struct fiops_rb_root {
};
#define FIOPS_RB_ROOT (struct fiops_rb_root) { .rb = RB_ROOT}

+enum wl_prio_t {
+ IDLE_WORKLOAD = 0,
+ BE_WORKLOAD = 1,
+ RT_WORKLOAD = 2,
+ FIOPS_PRIO_NR,
+};
+
struct fiops_data {
struct request_queue *queue;

- struct fiops_rb_root service_tree;
+ struct fiops_rb_root service_tree[FIOPS_PRIO_NR];

unsigned int busy_queues;
unsigned int in_flight[2];
@@ -60,13 +69,16 @@ struct fiops_ioc {
struct list_head fifo;

pid_t pid;
+ unsigned short ioprio;
+ enum wl_prio_t wl_type;
};

-#define ioc_service_tree(ioc) (&((ioc)->fiopsd->service_tree))
+#define ioc_service_tree(ioc) (&((ioc)->fiopsd->service_tree[(ioc)->wl_type]))
#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)

enum ioc_state_flags {
FIOPS_IOC_FLAG_on_rr = 0, /* on round-robin busy list */
+ FIOPS_IOC_FLAG_prio_changed, /* task priority has changed */
};

#define FIOPS_IOC_FNS(name) \
@@ -84,8 +96,18 @@ static inline int fiops_ioc_##name(const
}

FIOPS_IOC_FNS(on_rr);
+FIOPS_IOC_FNS(prio_changed);
#undef FIOPS_IOC_FNS

+enum wl_prio_t fiops_wl_type(short prio_class)
+{
+ if (prio_class == IOPRIO_CLASS_RT)
+ return RT_WORKLOAD;
+ if (prio_class == IOPRIO_CLASS_BE)
+ return BE_WORKLOAD;
+ return IDLE_WORKLOAD;
+}
+
static inline struct fiops_ioc *icq_to_cic(struct io_cq *icq)
{
/* cic->icq is the first member, %NULL will convert to %NULL */
@@ -298,6 +320,8 @@ static u64 fiops_scaled_vios(struct fiop
if (!rq_is_sync(rq))
vios = vios * fiopsd->async_scale / fiopsd->sync_scale;

+ vios += vios * (ioc->ioprio - IOPRIO_NORM) / VIOS_PRIO_SCALE;
+
return vios;
}

@@ -323,14 +347,19 @@ static int fiops_forced_dispatch(struct
{
struct fiops_ioc *ioc;
int dispatched = 0;
+ int i;

- while ((ioc = fiops_rb_first(&fiopsd->service_tree)) != NULL) {
- while (!list_empty(&ioc->fifo)) {
- fiops_dispatch_request(fiopsd, ioc);
- dispatched++;
+ for (i = RT_WORKLOAD; i >= IDLE_WORKLOAD; i--) {
+ while (!RB_EMPTY_ROOT(&fiopsd->service_tree[i].rb)) {
+ ioc = fiops_rb_first(&fiopsd->service_tree[i]);
+
+ while (!list_empty(&ioc->fifo)) {
+ fiops_dispatch_request(fiopsd, ioc);
+ dispatched++;
+ }
+ if (fiops_ioc_on_rr(ioc))
+ fiops_del_ioc_rr(fiopsd, ioc);
}
- if (fiops_ioc_on_rr(ioc))
- fiops_del_ioc_rr(fiopsd, ioc);
}
return dispatched;
}
@@ -338,10 +367,20 @@ static int fiops_forced_dispatch(struct
static struct fiops_ioc *fiops_select_ioc(struct fiops_data *fiopsd)
{
struct fiops_ioc *ioc;
+ struct fiops_rb_root *service_tree = NULL;
+ int i;
+
+ for (i = RT_WORKLOAD; i >= IDLE_WORKLOAD; i--) {
+ if (!RB_EMPTY_ROOT(&fiopsd->service_tree[i].rb)) {
+ service_tree = &fiopsd->service_tree[i];
+ break;
+ }
+ }

- if (RB_EMPTY_ROOT(&fiopsd->service_tree.rb))
+ if (!service_tree)
return NULL;
- ioc = fiops_rb_first(&fiopsd->service_tree);
+
+ ioc = fiops_rb_first(service_tree);
return ioc;
}

@@ -378,10 +417,49 @@ static int fiops_dispatch_requests(struc
return 1;
}

+static void fiops_init_prio_data(struct fiops_ioc *cic)
+{
+ struct task_struct *tsk = current;
+ struct io_context *ioc = cic->icq.ioc;
+ int ioprio_class;
+
+ if (!fiops_ioc_prio_changed(cic))
+ return;
+
+ ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
+ switch (ioprio_class) {
+ default:
+ printk(KERN_ERR "fiops: bad prio %x\n", ioprio_class);
+ case IOPRIO_CLASS_NONE:
+ /*
+ * no prio set, inherit CPU scheduling settings
+ */
+ cic->ioprio = task_nice_ioprio(tsk);
+ cic->wl_type = fiops_wl_type(task_nice_ioclass(tsk));
+ break;
+ case IOPRIO_CLASS_RT:
+ cic->ioprio = task_ioprio(ioc);
+ cic->wl_type = fiops_wl_type(IOPRIO_CLASS_RT);
+ break;
+ case IOPRIO_CLASS_BE:
+ cic->ioprio = task_ioprio(ioc);
+ cic->wl_type = fiops_wl_type(IOPRIO_CLASS_BE);
+ break;
+ case IOPRIO_CLASS_IDLE:
+ cic->wl_type = fiops_wl_type(IOPRIO_CLASS_IDLE);
+ cic->ioprio = 7;
+ break;
+ }
+
+ fiops_clear_ioc_prio_changed(cic);
+}
+
static void fiops_insert_request(struct request_queue *q, struct request *rq)
{
struct fiops_ioc *ioc = RQ_CIC(rq);

+ fiops_init_prio_data(ioc);
+
list_add_tail(&rq->queuelist, &ioc->fifo);

fiops_add_rq_rb(rq);
@@ -507,6 +585,7 @@ static void fiops_kick_queue(struct work
static void *fiops_init_queue(struct request_queue *q)
{
struct fiops_data *fiopsd;
+ int i;

fiopsd = kzalloc_node(sizeof(*fiopsd), GFP_KERNEL, q->node);
if (!fiopsd)
@@ -514,7 +593,8 @@ static void *fiops_init_queue(struct req

fiopsd->queue = q;

- fiopsd->service_tree = FIOPS_RB_ROOT;
+ for (i = IDLE_WORKLOAD; i <= RT_WORKLOAD; i++)
+ fiopsd->service_tree[i] = FIOPS_RB_ROOT;

INIT_WORK(&fiopsd->unplug_work, fiops_kick_queue);

@@ -538,6 +618,7 @@ static void fiops_init_icq(struct io_cq
ioc->fiopsd = fiopsd;

ioc->pid = current->pid;
+ fiops_mark_ioc_prio_changed(ioc);
}

/*


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