[PATCH 10/25] io-controller: cfq changes to use hierarchical fair queuing code in elevaotor layer

Make cfq hierarhical.
Signed-off-by: Nauman Rafique
Signed-off-by: Fabio Checconi
Signed-off-by: Paolo Valente
Signed-off-by: Aristeu Rozanski
Signed-off-by: Vivek Goyal
---
block/Kconfig.iosched | 8 ++++++
block/cfq-iosched.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++-
init/Kconfig | 2 +-
3 files changed, 69 insertions(+), 3 deletions(-)
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index dd5224d..a91a807 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -54,6 +54,14 @@ config IOSCHED_CFQ
working environment, suitable for desktop systems.
This is the default I/O scheduler.

+config IOSCHED_CFQ_HIER
+ bool "CFQ Hierarchical Scheduling support"
+ depends on IOSCHED_CFQ && CGROUPS
+ select GROUP_IOSCHED
+ default n
+ ---help---
+ Enable hierarhical scheduling in cfq.
+
choice
prompt "Default I/O scheduler"
default DEFAULT_CFQ
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 6ddc882..02b5cd5 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1222,6 +1222,60 @@ static void cfq_ioc_set_ioprio(struct io_context *ioc)
ioc->ioprio_changed = 0;
}

+#ifdef CONFIG_IOSCHED_CFQ_HIER
+static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
+{
+ struct cfq_queue *async_cfqq = cic_to_cfqq(cic, 0);
+ struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
+ struct cfq_data *cfqd = cic->key;
+ struct io_group *iog, *__iog;
+ unsigned long flags;
+ struct request_queue *q;
+
+ if (unlikely(!cfqd))
+ return;
+
+ q = cfqd->queue;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ iog = io_get_io_group(q, 0);
+
+ if (async_cfqq != NULL) {
+ __iog = cfqq_to_io_group(async_cfqq);
+ if (iog != __iog) {
+ /* cgroup changed, drop the reference to async queue */
+ cic_set_cfqq(cic, NULL, 0);
+ cfq_put_queue(async_cfqq);
+ }
+ }
+
+ if (sync_cfqq != NULL) {
+ __iog = cfqq_to_io_group(sync_cfqq);
+
+ /*
+ * Drop reference to sync queue. A new sync queue will
+ * be assigned in new group upon arrival of a fresh request.
+ * If old queue has got requests, those reuests will be
+ * dispatched over a period of time and queue will be freed
+ * automatically.
+ */
+ if (iog != __iog) {
+ cic_set_cfqq(cic, NULL, 1);
+ cfq_put_queue(sync_cfqq);
+ }
+ }
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static void cfq_ioc_set_cgroup(struct io_context *ioc)
+{
+ call_for_each_cic(ioc, changed_cgroup);
+ ioc->cgroup_changed = 0;
+}
+#endif /* CONFIG_IOSCHED_CFQ_HIER */
+
static struct cfq_queue *
cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
struct io_context *ioc, gfp_t gfp_mask)
@@ -1232,7 +1286,7 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
struct io_queue *ioq = NULL, *new_ioq = NULL;
struct io_group *iog = NULL;
retry:
- iog = io_get_io_group(q);
+ iog = io_get_io_group(q, 1);

cic = cfq_cic_lookup(cfqd, ioc);
/* cic always exists here */
@@ -1334,7 +1388,7 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
const int ioprio_class = task_ioprio_class(ioc);
struct cfq_queue *async_cfqq = NULL;
struct cfq_queue *cfqq = NULL;
- struct io_group *iog = io_get_io_group(cfqd->queue);
+ struct io_group *iog = io_get_io_group(cfqd->queue, 1);

if (!is_sync) {
async_cfqq = io_group_async_queue_prio(iog, ioprio_class,
@@ -1493,6 +1547,10 @@ out:
smp_read_barrier_depends();
if (unlikely(ioc->ioprio_changed))
cfq_ioc_set_ioprio(ioc);
+#ifdef CONFIG_IOSCHED_CFQ_HIER
+ if (unlikely(ioc->cgroup_changed))
+ cfq_ioc_set_cgroup(ioc);
+#endif
return cic;
err_free:
cfq_cic_free(cic);
diff --git a/init/Kconfig b/init/Kconfig
index a380f46..eaa44db 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -613,7 +613,7 @@ config CGROUP_MEM_RES_CTLR_SWAP
size is 4096bytes, 512k per 1Gbytes of swap.

config GROUP_IOSCHED
- bool "Group IO Scheduler"
+ bool
depends on CGROUPS && ELV_FAIR_QUEUING
default n
---help---
--
1.6.0.6
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