Re: [PATCH] cfq: get rid of cfqq hash

From: Jens Axboe
Date: Wed Apr 25 2007 - 03:28:24 EST


On Wed, Apr 25 2007, Jens Axboe wrote:
> On Tue, Apr 24 2007, Vasily Tarasov wrote:
> > @@ -1806,7 +1765,11 @@ static int cfq_may_queue(request_queue_t
> > * so just lookup a possibly existing queue, or return 'may queue'
> > * if that fails
> > */
> > - cfqq = cfq_find_cfq_hash(cfqd, key, tsk->ioprio);
> > + cic = cfq_get_io_context_noalloc(cfqd, tsk);
> > + if (!cic)
> > + return ELV_MQUEUE_MAY;
> > +
> > + cfqq = cic->cfqq[rw & REQ_RW_SYNC];
> > if (cfqq) {
> > cfq_init_prio_data(cfqq);
> > cfq_prio_boost(cfqq);
>
> Ahem, how well did you test this patch?

Incremental update to get things working below.

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ed1ce43..17e4660 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -202,6 +202,18 @@ static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
static struct cfq_io_context *cfq_cic_rb_lookup(struct cfq_data *,
struct io_context *);

+static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
+ int is_sync)
+{
+ return cic->cfqq[!!is_sync];
+}
+
+static inline void cic_set_cfqq(struct cfq_io_context *cic,
+ struct cfq_queue *cfqq, int is_sync)
+{
+ cic->cfqq[!!is_sync] = cfqq;
+}
+
/*
* scheduler run of queue, if there are requests pending and no one in the
* driver that will restart queueing
@@ -582,7 +594,7 @@ cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
if (!cic)
return NULL;

- cfqq = cic->cfqq[bio_sync(bio)];
+ cfqq = cic_to_cfqq(cic, bio_sync(bio));
if (cfqq) {
sector_t sector = bio->bi_sector + bio_sectors(bio);

@@ -693,7 +705,7 @@ static int cfq_allow_merge(request_queue_t *q, struct request *rq,
if (!cic)
return 0;

- cfqq = cic->cfqq[bio_sync(bio)];
+ cfqq = cic_to_cfqq(cic, bio_sync(bio));
if (cfqq == RQ_CFQQ(rq))
return 1;

@@ -1330,7 +1342,7 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk,
retry:
cic = cfq_cic_rb_lookup(cfqd, tsk->io_context);
/* cic always exists here */
- cfqq = cic->cfqq[is_sync];
+ cfqq = cic_to_cfqq(cic, is_sync);

if (!cfqq) {
if (new_cfqq) {
@@ -1821,7 +1833,7 @@ static int cfq_may_queue(request_queue_t *q, int rw)
if (!cic)
return ELV_MQUEUE_MAY;

- cfqq = cic->cfqq[rw & REQ_RW_SYNC];
+ cfqq = cic_to_cfqq(cic, rw & REQ_RW_SYNC);
if (cfqq) {
cfq_init_prio_data(cfqq);
cfq_prio_boost(cfqq);
@@ -1877,15 +1889,15 @@ cfq_set_request(request_queue_t *q, struct request *rq, gfp_t gfp_mask)
if (!cic)
goto queue_fail;

- if (!cic->cfqq[is_sync]) {
+ cfqq = cic_to_cfqq(cic, is_sync);
+ if (!cfqq) {
cfqq = cfq_get_queue(cfqd, is_sync, tsk, gfp_mask);

if (!cfqq)
goto queue_fail;

- cic->cfqq[is_sync] = cfqq;
- } else
- cfqq = cic->cfqq[is_sync];
+ cic_set_cfqq(cic, cfqq, is_sync);
+ }

cfqq->allocated[rw]++;
cfq_clear_cfqq_must_alloc(cfqq);

--
Jens Axboe

-
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