dontpanic
4ebacbb52c
sys-kernel/linux-server] Added an IO latency patch for the cfq ioscheduler. Please note this patch is backported from the 2.6.32 kernel source, so this patch should be dropped from the 2.6.32 ebuilds.
113 lines
3.3 KiB
Diff
113 lines
3.3 KiB
Diff
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
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index 87276eb..57ed6fc 100644
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--- a/block/cfq-iosched.c
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+++ b/block/cfq-iosched.c
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@@ -140,7 +140,7 @@ struct cfq_data {
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*/
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unsigned int busy_rt_queues;
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- int rq_in_driver;
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+ int rq_in_driver[2];
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int sync_flight;
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/*
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@@ -239,6 +239,11 @@ static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
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static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
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struct io_context *);
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+static inline int rq_in_driver(struct cfq_data *cfqd)
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+{
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+ return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
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+}
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+
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static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
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int is_sync)
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{
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@@ -760,9 +765,9 @@ static void cfq_activate_request(struct request_queue *q, struct request *rq)
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{
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struct cfq_data *cfqd = q->elevator->elevator_data;
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- cfqd->rq_in_driver++;
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+ cfqd->rq_in_driver[rq_is_sync(rq)]++;
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cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
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- cfqd->rq_in_driver);
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+ rq_in_driver(cfqd));
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cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
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}
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@@ -770,11 +775,12 @@ static void cfq_activate_request(struct request_queue *q, struct request *rq)
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static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
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{
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struct cfq_data *cfqd = q->elevator->elevator_data;
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+ const int sync = rq_is_sync(rq);
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- WARN_ON(!cfqd->rq_in_driver);
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- cfqd->rq_in_driver--;
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+ WARN_ON(!cfqd->rq_in_driver[sync]);
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+ cfqd->rq_in_driver[sync]--;
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cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
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- cfqd->rq_in_driver);
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+ rq_in_driver(cfqd));
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}
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static void cfq_remove_request(struct request *rq)
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@@ -1080,7 +1086,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
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/*
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* still requests with the driver, don't idle
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*/
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- if (cfqd->rq_in_driver)
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+ if (rq_in_driver(cfqd))
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return;
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/*
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@@ -1312,6 +1318,12 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
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return 0;
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/*
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+ * Drain async requests before we start sync IO
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+ */
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+ if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
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+ return 0;
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+
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+ /*
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* If this is an async queue and we have sync IO in flight, let it wait
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*/
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if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
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@@ -2130,11 +2142,11 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
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*/
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static void cfq_update_hw_tag(struct cfq_data *cfqd)
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{
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- if (cfqd->rq_in_driver > cfqd->rq_in_driver_peak)
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- cfqd->rq_in_driver_peak = cfqd->rq_in_driver;
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+ if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
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+ cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
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if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
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- cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
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+ rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
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return;
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if (cfqd->hw_tag_samples++ < 50)
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@@ -2161,9 +2173,9 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
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cfq_update_hw_tag(cfqd);
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- WARN_ON(!cfqd->rq_in_driver);
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+ WARN_ON(!cfqd->rq_in_driver[sync]);
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WARN_ON(!cfqq->dispatched);
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- cfqd->rq_in_driver--;
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+ cfqd->rq_in_driver[sync]--;
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cfqq->dispatched--;
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if (cfq_cfqq_sync(cfqq))
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@@ -2197,7 +2209,7 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
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cfq_arm_slice_timer(cfqd);
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}
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- if (!cfqd->rq_in_driver)
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+ if (!rq_in_driver(cfqd))
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cfq_schedule_dispatch(cfqd);
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}
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