From: Jeff Moyer <jmoyer@redhat.com>
Date: Tue, 3 Nov 2009 11:36:41 -0500
Subject: [block] cfq: calc seek_mean per cfq_queue not per cfq_io_context
Message-id: 1257266206-24003-8-git-send-email-jmoyer@redhat.com
O-Subject: [PATCH 07/12] cfq: calculate the seek_mean per cfq_queue not per cfq_io_context
Bugzilla: 456181 448130 427709
RH-Acked-by: Josef Bacik <josef@redhat.com>
RH-Acked-by: Vivek Goyal <vgoyal@redhat.com>

commit b2c18e1e08a5a9663094d57bb4be2f02226ee61c
Author: Jeff Moyer <jmoyer@redhat.com>
Date:   Fri Oct 23 17:14:49 2009 -0400

    cfq: calculate the seek_mean per cfq_queue not per cfq_io_context

    async cfq_queue's are already shared between processes within the same
    priority, and forthcoming patches will change the mapping of cic to sync
    cfq_queue from 1:1 to 1:N.  So, calculate the seekiness of a process
    based on the cfq_queue instead of the cfq_io_context.

    Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
    Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 805b55c..7834e08 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -207,6 +207,11 @@ struct cfq_queue {
 	unsigned short ioprio, org_ioprio;
 	unsigned short ioprio_class, org_ioprio_class;
 
+	unsigned int seek_samples;
+	u64 seek_total;
+	sector_t seek_mean;
+	sector_t last_request_pos;
+
 	/* various state flags, see below */
 	unsigned int flags;
 };
@@ -964,16 +969,16 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
 		return cfqd->last_position - rq->sector;
 }
 
-#define CIC_SEEK_THR   8 * 1024
-#define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
+#define CFQQ_SEEK_THR   8 * 1024
+#define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
 
-static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
+static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+			       struct request *rq)
 {
-	struct cfq_io_context *cic = cfqd->active_cic;
-	sector_t sdist = cic->seek_mean;
+	sector_t sdist = cfqq->seek_mean;
 
-	if (!sample_valid(cic->seek_samples))
-		sdist = CIC_SEEK_THR;
+	if (!sample_valid(cfqq->seek_samples))
+		sdist = CFQQ_SEEK_THR;
 
 	return cfq_dist_from_last(cfqd, rq) <= sdist;
 }
@@ -1044,7 +1049,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
 	 * will contain the closest sector.
 	 */
 	__cfqq = rb_entry(parent, struct cfq_queue, p_node);
-	if (cfq_rq_close(cfqd, __cfqq->next_crq->request))
+	if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_crq->request))
 		return __cfqq;
 
 	if (__cfqq->next_crq->request->sector < sector)
@@ -1055,7 +1060,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
 		return NULL;
 
 	__cfqq = rb_entry(node, struct cfq_queue, p_node);
-	if (cfq_rq_close(cfqd, __cfqq->next_crq->request))
+	if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_crq->request))
 		return __cfqq;
 
 	return NULL;
@@ -1078,13 +1083,6 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
 	struct cfq_queue *cfqq;
 
 	/*
-	 * A valid cfq_io_context is necessary to compare requests against
-	 * the seek_mean of the current cfqq.
-	 */
-	if (!cfqd->active_cic)
-		return NULL;
-
-	/*
 	 * We should notice if some of the queues are cooperating, eg
 	 * working closely on the same area of the disk.  In that case,
 	 * we can group them together and don't waste time idling.
@@ -1136,7 +1134,7 @@ static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 	 * fair distribution of slice time for a process doing back-to-back
 	 * seeks. so allow a little bit of time for him to submit a new rq
 	 */
-	if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
+	if (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq))
 		sl = min(sl, msecs_to_jiffies(2));
 
 	mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
@@ -1848,33 +1846,33 @@ cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
 }
 
 static void
-cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
+cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 		       struct cfq_rq *crq)
 {
 	sector_t sdist;
 	u64 total;
 
-	if (!cic->last_request_pos)
+	if (!cfqq->last_request_pos)
 		sdist = 0;
-	else if (cic->last_request_pos < crq->request->sector)
-		sdist = crq->request->sector - cic->last_request_pos;
+	else if (cfqq->last_request_pos < crq->request->sector)
+		sdist = crq->request->sector - cfqq->last_request_pos;
 	else
-		sdist = cic->last_request_pos - crq->request->sector;
+		sdist = cfqq->last_request_pos - crq->request->sector;
 
 	/*
 	 * Don't allow the seek distance to get too large from the
 	 * odd fragment, pagein, etc
 	 */
-	if (cic->seek_samples <= 60) /* second&third seek */
-		sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
+	if (cfqq->seek_samples <= 60) /* second&third seek */
+		sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*1024);
 	else
-		sdist = min(sdist, (cic->seek_mean * 4)	+ 2*1024*64);
+		sdist = min(sdist, (cfqq->seek_mean * 4) + 2*1024*64);
 
-	cic->seek_samples = (7*cic->seek_samples + 256) / 8;
-	cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
-	total = cic->seek_total + (cic->seek_samples/2);
-	do_div(total, cic->seek_samples);
-	cic->seek_mean = (sector_t)total;
+	cfqq->seek_samples = (7*cfqq->seek_samples + 256) / 8;
+	cfqq->seek_total = (7*cfqq->seek_total + (u64)256*sdist) / 8;
+	total = cfqq->seek_total + (cfqq->seek_samples/2);
+	do_div(total, cfqq->seek_samples);
+	cfqq->seek_mean = (sector_t)total;
 }
 
 /*
@@ -1888,7 +1886,7 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 	int enable_idle = cfq_cfqq_idle_window(cfqq);
 
 	if (!cic->ioc->task || !cfqd->cfq_slice_idle ||
-	    (cfqd->hw_tag && CIC_SEEKY(cic)))
+	    (cfqd->hw_tag && CFQQ_SEEKY(cfqq)))
 		enable_idle = 0;
 	else if (sample_valid(cic->ttime_samples)) {
 		if (cic->ttime_mean > cfqd->cfq_slice_idle)
@@ -1932,7 +1930,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
 	if (cfq_crq_is_sync(crq) && !cfq_cfqq_sync(cfqq))
 		return 1;
 
-	if (cfq_rq_close(cfqd, crq->request))
+	if (cfq_rq_close(cfqd, cfqq, crq->request))
 		return 1;
 
 	return 0;
@@ -1998,11 +1996,11 @@ cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 	}
 
 	cfq_update_io_thinktime(cfqd, cic);
-	cfq_update_io_seektime(cfqd, cic, crq);
+	cfq_update_io_seektime(cfqd, cfqq, crq);
 	cfq_update_idle_window(cfqd, cfqq, cic);
 
 	cic->last_queue = jiffies;
-	cic->last_request_pos = crq->request->sector + crq->request->nr_sectors;
+	cfqq->last_request_pos = crq->request->sector + crq->request->nr_sectors;
 
 	if (cfqq == cfqd->active_queue) {
 		/*
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 748ff68..c005442 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -64,17 +64,12 @@ struct cfq_io_context {
 	struct io_context *ioc;
 
 	unsigned long last_end_request;
-	sector_t last_request_pos;
  	unsigned long last_queue;
 
 	unsigned long ttime_total;
 	unsigned long ttime_samples;
 	unsigned long ttime_mean;
 
-	unsigned int seek_samples;
-	u64 seek_total;
-	sector_t seek_mean;
-
 	struct list_head queue_list;
 
 	void (*dtor)(struct io_context *); /* destructor */