* [PATCH 0/7] [RFC] iosched: make a difference between read/readahead requests
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak
Hi Jens,
This patchset does two jobs:
1) do io schedule differently on READ/READA requests.
- to help improve I/O latency and throughput
2) do notification/action on READA => READ events
- to make the elevators better informed
- to prevent the priority inversion problem
- also brings some CPU overheads*
(*) I'm not able to provide numbers at the moment.
Our server is not up for testing these days. But sure will for the next time.
The patches come in two groups:
1) explicitly schedule READA requests
Note: currently only the deadline elevator is touched.
[PATCH 1/7] iosched: introduce WRITEA
[PATCH 2/7] iosched: introduce parameter deadline.reada_expire
[PATCH 3/7] iosched: introduce deadline_add_drq_fifo()
[PATCH 4/7] iosched: submit READA requests on possible readahead code path
2) notify/act on pending reads
Naming issue: how about pending_read/need_page/... for kick_page?
[PATCH 5/7] iosched: introduce elv_kick_page()
[PATCH 6/7] iosched: run elv_kick_page() on sync read
[PATCH 7/7] iosched: introduce deadline_kick_page()
Most overheads should be in functions deadline_kick_page() and
deadline_add_drq_fifo(). I'll explore the details later.
Any comments are welcome, thanks.
Fengguang Wu
--
Dept. Automation University of Science and Technology of China
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 1/7] iosched: introduce WRITEA
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak,
Wu Fengguang
[-- Attachment #1: iosched-reada-redef.patch --]
[-- Type: text/plain, Size: 911 bytes --]
Introduce WRITEA as 3, and redefine SWRITE as 5.
I'm not sure if WRITEA will ever be used, though it would be better to
redefine SWRITE to avoid possible conflict with BIO_RW_AHEAD.
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
--- linux-2.6.17-rc6-mm2.orig/include/linux/fs.h
+++ linux-2.6.17-rc6-mm2/include/linux/fs.h
@@ -74,8 +74,9 @@ extern int dir_notify_enable;
#define READ 0
#define WRITE 1
#define READA 2 /* read-ahead - don't block if no resources */
-#define SWRITE 3 /* for ll_rw_block() - wait for buffer lock */
+#define WRITEA 3 /* write-ahead - don't block if no resources */
#define SPECIAL 4 /* For non-blockdevice requests in request queue */
+#define SWRITE 5 /* for ll_rw_block() - wait for buffer lock */
#define READ_SYNC (READ | (1 << BIO_RW_SYNC))
#define WRITE_SYNC (WRITE | (1 << BIO_RW_SYNC))
#define WRITE_BARRIER ((1 << BIO_RW) | (1 << BIO_RW_BARRIER))
--
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 1/7] iosched: introduce WRITEA
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak,
Wu Fengguang
[-- Attachment #1: iosched-reada-redef.patch --]
[-- Type: text/plain, Size: 911 bytes --]
Introduce WRITEA as 3, and redefine SWRITE as 5.
I'm not sure if WRITEA will ever be used, though it would be better to
redefine SWRITE to avoid possible conflict with BIO_RW_AHEAD.
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
--- linux-2.6.17-rc6-mm2.orig/include/linux/fs.h
+++ linux-2.6.17-rc6-mm2/include/linux/fs.h
@@ -74,8 +74,9 @@ extern int dir_notify_enable;
#define READ 0
#define WRITE 1
#define READA 2 /* read-ahead - don't block if no resources */
-#define SWRITE 3 /* for ll_rw_block() - wait for buffer lock */
+#define WRITEA 3 /* write-ahead - don't block if no resources */
#define SPECIAL 4 /* For non-blockdevice requests in request queue */
+#define SWRITE 5 /* for ll_rw_block() - wait for buffer lock */
#define READ_SYNC (READ | (1 << BIO_RW_SYNC))
#define WRITE_SYNC (WRITE | (1 << BIO_RW_SYNC))
#define WRITE_BARRIER ((1 << BIO_RW) | (1 << BIO_RW_BARRIER))
--
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 4/7] iosched: submit READA requests on possible readahead code path
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak,
Wu Fengguang
[-- Attachment #1: iosched-submit-reada-on-possible-readahead-path.patch --]
[-- Type: text/plain, Size: 2119 bytes --]
Change the request type from READ to READA in possible readahead code paths.
- call mpage_bio_submit(READA) in mpage_readpages()
- call submit_bio(READA) in swap_readpage()
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
fs/mpage.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)
--- linux-2.6.17-mm1.orig/fs/mpage.c
+++ linux-2.6.17-mm1/fs/mpage.c
@@ -302,7 +302,7 @@ do_mpage_readpage(struct bio *bio, struc
* This page will go to BIO. Do we need to send this BIO off first?
*/
if (bio && (*last_block_in_bio != blocks[0] - 1))
- bio = mpage_bio_submit(READ, bio);
+ bio = mpage_bio_submit(READA, bio);
alloc_new:
if (bio == NULL) {
@@ -315,12 +315,12 @@ alloc_new:
length = first_hole << blkbits;
if (bio_add_page(bio, page, length, 0) < length) {
- bio = mpage_bio_submit(READ, bio);
+ bio = mpage_bio_submit(READA, bio);
goto alloc_new;
}
if (buffer_boundary(map_bh) || (first_hole != blocks_per_page))
- bio = mpage_bio_submit(READ, bio);
+ bio = mpage_bio_submit(READA, bio);
else
*last_block_in_bio = blocks[blocks_per_page - 1];
out:
@@ -328,7 +328,7 @@ out:
confused:
if (bio)
- bio = mpage_bio_submit(READ, bio);
+ bio = mpage_bio_submit(READA, bio);
if (!PageUptodate(page))
block_read_full_page(page, get_block);
else
@@ -418,7 +418,7 @@ mpage_readpages(struct address_space *ma
pagevec_lru_add(&lru_pvec);
BUG_ON(!list_empty(pages));
if (bio)
- mpage_bio_submit(READ, bio);
+ mpage_bio_submit(READA, bio);
return 0;
}
EXPORT_SYMBOL(mpage_readpages);
@@ -437,7 +437,7 @@ int mpage_readpage(struct page *page, ge
bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
&map_bh, &first_logical_block, get_block);
if (bio)
- mpage_bio_submit(READ, bio);
+ mpage_bio_submit(READA, bio);
return 0;
}
EXPORT_SYMBOL(mpage_readpage);
--- linux-2.6.17-mm1.orig/mm/page_io.c
+++ linux-2.6.17-mm1/mm/page_io.c
@@ -124,7 +124,7 @@ int swap_readpage(struct file *file, str
goto out;
}
inc_page_state(pswpin);
- submit_bio(READ, bio);
+ submit_bio(READA, bio);
out:
return ret;
}
--
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 4/7] iosched: submit READA requests on possible readahead code path
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak,
Wu Fengguang
[-- Attachment #1: iosched-submit-reada-on-possible-readahead-path.patch --]
[-- Type: text/plain, Size: 2119 bytes --]
Change the request type from READ to READA in possible readahead code paths.
- call mpage_bio_submit(READA) in mpage_readpages()
- call submit_bio(READA) in swap_readpage()
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
fs/mpage.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)
--- linux-2.6.17-mm1.orig/fs/mpage.c
+++ linux-2.6.17-mm1/fs/mpage.c
@@ -302,7 +302,7 @@ do_mpage_readpage(struct bio *bio, struc
* This page will go to BIO. Do we need to send this BIO off first?
*/
if (bio && (*last_block_in_bio != blocks[0] - 1))
- bio = mpage_bio_submit(READ, bio);
+ bio = mpage_bio_submit(READA, bio);
alloc_new:
if (bio == NULL) {
@@ -315,12 +315,12 @@ alloc_new:
length = first_hole << blkbits;
if (bio_add_page(bio, page, length, 0) < length) {
- bio = mpage_bio_submit(READ, bio);
+ bio = mpage_bio_submit(READA, bio);
goto alloc_new;
}
if (buffer_boundary(map_bh) || (first_hole != blocks_per_page))
- bio = mpage_bio_submit(READ, bio);
+ bio = mpage_bio_submit(READA, bio);
else
*last_block_in_bio = blocks[blocks_per_page - 1];
out:
@@ -328,7 +328,7 @@ out:
confused:
if (bio)
- bio = mpage_bio_submit(READ, bio);
+ bio = mpage_bio_submit(READA, bio);
if (!PageUptodate(page))
block_read_full_page(page, get_block);
else
@@ -418,7 +418,7 @@ mpage_readpages(struct address_space *ma
pagevec_lru_add(&lru_pvec);
BUG_ON(!list_empty(pages));
if (bio)
- mpage_bio_submit(READ, bio);
+ mpage_bio_submit(READA, bio);
return 0;
}
EXPORT_SYMBOL(mpage_readpages);
@@ -437,7 +437,7 @@ int mpage_readpage(struct page *page, ge
bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
&map_bh, &first_logical_block, get_block);
if (bio)
- mpage_bio_submit(READ, bio);
+ mpage_bio_submit(READA, bio);
return 0;
}
EXPORT_SYMBOL(mpage_readpage);
--- linux-2.6.17-mm1.orig/mm/page_io.c
+++ linux-2.6.17-mm1/mm/page_io.c
@@ -124,7 +124,7 @@ int swap_readpage(struct file *file, str
goto out;
}
inc_page_state(pswpin);
- submit_bio(READ, bio);
+ submit_bio(READA, bio);
out:
return ret;
}
--
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 5/7] iosched: introduce elv_kick_page()
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak,
Wu Fengguang
[-- Attachment #1: iosched-kick-page-elevator.patch --]
[-- Type: text/plain, Size: 2416 bytes --]
Introduce elv_kick_page() to turn a possibly READA request into READ.
The underlying elevator_kick_page_fn() should also reschedule the request
if necessary.
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
block/ll_rw_blk.c | 8 ++++++++
fs/buffer.c | 5 +++--
include/linux/elevator.h | 2 ++
3 files changed, 13 insertions(+), 2 deletions(-)
--- linux-2.6.17-rc5-mm3.orig/include/linux/elevator.h
+++ linux-2.6.17-rc5-mm3/include/linux/elevator.h
@@ -20,6 +20,7 @@ typedef int (elevator_set_req_fn) (reque
typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *);
typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *);
+typedef int (elevator_kick_page_fn) (request_queue_t *, struct page *);
typedef int (elevator_init_fn) (request_queue_t *, elevator_t *);
typedef void (elevator_exit_fn) (elevator_t *);
@@ -34,6 +35,7 @@ struct elevator_ops
elevator_add_req_fn *elevator_add_req_fn;
elevator_activate_req_fn *elevator_activate_req_fn;
elevator_deactivate_req_fn *elevator_deactivate_req_fn;
+ elevator_kick_page_fn *elevator_kick_page_fn;
elevator_queue_empty_fn *elevator_queue_empty_fn;
elevator_completed_req_fn *elevator_completed_req_fn;
@@ -91,6 +93,7 @@ extern void elv_dispatch_sort(request_qu
extern void elv_add_request(request_queue_t *, struct request *, int, int);
extern void __elv_add_request(request_queue_t *, struct request *, int, int);
extern void elv_insert(request_queue_t *, struct request *, int);
+extern void elv_kick_page(request_queue_t *, struct page *);
extern int elv_merge(request_queue_t *, struct request **, struct bio *);
extern void elv_merge_requests(request_queue_t *, struct request *,
struct request *);
--- linux-2.6.17-rc5-mm3.orig/block/elevator.c
+++ linux-2.6.17-rc5-mm3/block/elevator.c
@@ -468,6 +468,16 @@ void elv_add_request(request_queue_t *q,
spin_unlock_irqrestore(q->queue_lock, flags);
}
+void elv_kick_page(request_queue_t *q, struct page *page)
+{
+ if (page && q->elevator && q->elevator->ops->elevator_kick_page_fn) {
+ spin_lock_irq(q->queue_lock);
+ q->elevator->ops->elevator_kick_page_fn(q, page);
+ spin_unlock_irq(q->queue_lock);
+ }
+
+}
+
static inline struct request *__elv_next_request(request_queue_t *q)
{
struct request *rq;
--
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 5/7] iosched: introduce elv_kick_page()
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak,
Wu Fengguang
[-- Attachment #1: iosched-kick-page-elevator.patch --]
[-- Type: text/plain, Size: 2416 bytes --]
Introduce elv_kick_page() to turn a possibly READA request into READ.
The underlying elevator_kick_page_fn() should also reschedule the request
if necessary.
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
block/ll_rw_blk.c | 8 ++++++++
fs/buffer.c | 5 +++--
include/linux/elevator.h | 2 ++
3 files changed, 13 insertions(+), 2 deletions(-)
--- linux-2.6.17-rc5-mm3.orig/include/linux/elevator.h
+++ linux-2.6.17-rc5-mm3/include/linux/elevator.h
@@ -20,6 +20,7 @@ typedef int (elevator_set_req_fn) (reque
typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *);
typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *);
+typedef int (elevator_kick_page_fn) (request_queue_t *, struct page *);
typedef int (elevator_init_fn) (request_queue_t *, elevator_t *);
typedef void (elevator_exit_fn) (elevator_t *);
@@ -34,6 +35,7 @@ struct elevator_ops
elevator_add_req_fn *elevator_add_req_fn;
elevator_activate_req_fn *elevator_activate_req_fn;
elevator_deactivate_req_fn *elevator_deactivate_req_fn;
+ elevator_kick_page_fn *elevator_kick_page_fn;
elevator_queue_empty_fn *elevator_queue_empty_fn;
elevator_completed_req_fn *elevator_completed_req_fn;
@@ -91,6 +93,7 @@ extern void elv_dispatch_sort(request_qu
extern void elv_add_request(request_queue_t *, struct request *, int, int);
extern void __elv_add_request(request_queue_t *, struct request *, int, int);
extern void elv_insert(request_queue_t *, struct request *, int);
+extern void elv_kick_page(request_queue_t *, struct page *);
extern int elv_merge(request_queue_t *, struct request **, struct bio *);
extern void elv_merge_requests(request_queue_t *, struct request *,
struct request *);
--- linux-2.6.17-rc5-mm3.orig/block/elevator.c
+++ linux-2.6.17-rc5-mm3/block/elevator.c
@@ -468,6 +468,16 @@ void elv_add_request(request_queue_t *q,
spin_unlock_irqrestore(q->queue_lock, flags);
}
+void elv_kick_page(request_queue_t *q, struct page *page)
+{
+ if (page && q->elevator && q->elevator->ops->elevator_kick_page_fn) {
+ spin_lock_irq(q->queue_lock);
+ q->elevator->ops->elevator_kick_page_fn(q, page);
+ spin_unlock_irq(q->queue_lock);
+ }
+
+}
+
static inline struct request *__elv_next_request(request_queue_t *q)
{
struct request *rq;
--
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 7/7] iosched: introduce deadline_kick_page()
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak,
Wu Fengguang
[-- Attachment #1: iosched-kick-page-deadline.patch --]
[-- Type: text/plain, Size: 1891 bytes --]
Introduce deadline_kick_page() to
- find the request containing the page
- remove its BIO_RW_AHEAD flag
- reschedule if it was of type READA
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
block/deadline-iosched.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 43 insertions(+), 2 deletions(-)
--- linux-2.6.17-rc6-mm2.orig/block/deadline-iosched.c
+++ linux-2.6.17-rc6-mm2/block/deadline-iosched.c
@@ -317,6 +317,44 @@ deadline_add_request(struct request_queu
}
/*
+ * We have a pending read on @page,
+ * find the corresponding request of type READA,
+ * promote it to READ, and reschedule it.
+ */
+static int
+deadline_kick_page(struct request_queue *q, struct page *page)
+{
+ struct deadline_data *dd = q->elevator->elevator_data;
+ struct deadline_rq *drq;
+ struct request *rq;
+ struct list_head *pos;
+ struct bio_vec *bvec;
+ struct bio *bio;
+ int i;
+
+ list_for_each(pos, &dd->fifo_list[READ]) {
+ drq = list_entry_fifo(pos);
+ rq = drq->request;
+ if (rq->flags & (1 << BIO_RW_AHEAD)) {
+ rq_for_each_bio(bio, rq) {
+ bio_for_each_segment(bvec, bio, i) {
+ if (page == bvec->bv_page)
+ goto found;
+ }
+ }
+ }
+ }
+
+ return -1;
+
+found:
+ rq->flags &= ~(1 << BIO_RW_AHEAD);
+ list_del(&drq->fifo);
+ deadline_add_drq_fifo(dd, rq);
+ return 0;
+}
+
+/*
* remove rq from rbtree, fifo, and hash
*/
static void deadline_remove_request(request_queue_t *q, struct request *rq)
@@ -794,6 +832,7 @@ static struct elevator_type iosched_dead
.elevator_merge_req_fn = deadline_merged_requests,
.elevator_dispatch_fn = deadline_dispatch_requests,
.elevator_add_req_fn = deadline_add_request,
+ .elevator_kick_page_fn = deadline_kick_page,
.elevator_queue_empty_fn = deadline_queue_empty,
.elevator_former_req_fn = deadline_former_request,
.elevator_latter_req_fn = deadline_latter_request,
--
^ permalink raw reply [flat|nested] 11+ messages in thread* [PATCH 7/7] iosched: introduce deadline_kick_page()
@ 2006-06-24 8:20 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-24 8:20 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak,
Wu Fengguang
[-- Attachment #1: iosched-kick-page-deadline.patch --]
[-- Type: text/plain, Size: 1891 bytes --]
Introduce deadline_kick_page() to
- find the request containing the page
- remove its BIO_RW_AHEAD flag
- reschedule if it was of type READA
Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---
block/deadline-iosched.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 43 insertions(+), 2 deletions(-)
--- linux-2.6.17-rc6-mm2.orig/block/deadline-iosched.c
+++ linux-2.6.17-rc6-mm2/block/deadline-iosched.c
@@ -317,6 +317,44 @@ deadline_add_request(struct request_queu
}
/*
+ * We have a pending read on @page,
+ * find the corresponding request of type READA,
+ * promote it to READ, and reschedule it.
+ */
+static int
+deadline_kick_page(struct request_queue *q, struct page *page)
+{
+ struct deadline_data *dd = q->elevator->elevator_data;
+ struct deadline_rq *drq;
+ struct request *rq;
+ struct list_head *pos;
+ struct bio_vec *bvec;
+ struct bio *bio;
+ int i;
+
+ list_for_each(pos, &dd->fifo_list[READ]) {
+ drq = list_entry_fifo(pos);
+ rq = drq->request;
+ if (rq->flags & (1 << BIO_RW_AHEAD)) {
+ rq_for_each_bio(bio, rq) {
+ bio_for_each_segment(bvec, bio, i) {
+ if (page == bvec->bv_page)
+ goto found;
+ }
+ }
+ }
+ }
+
+ return -1;
+
+found:
+ rq->flags &= ~(1 << BIO_RW_AHEAD);
+ list_del(&drq->fifo);
+ deadline_add_drq_fifo(dd, rq);
+ return 0;
+}
+
+/*
* remove rq from rbtree, fifo, and hash
*/
static void deadline_remove_request(request_queue_t *q, struct request *rq)
@@ -794,6 +832,7 @@ static struct elevator_type iosched_dead
.elevator_merge_req_fn = deadline_merged_requests,
.elevator_dispatch_fn = deadline_dispatch_requests,
.elevator_add_req_fn = deadline_add_request,
+ .elevator_kick_page_fn = deadline_kick_page,
.elevator_queue_empty_fn = deadline_queue_empty,
.elevator_former_req_fn = deadline_former_request,
.elevator_latter_req_fn = deadline_latter_request,
--
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 7/7] iosched: introduce deadline_kick_page()
@ 2006-06-24 11:01 ` Jens Axboe
2006-06-25 6:32 ` Fengguang Wu
0 siblings, 1 reply; 11+ messages in thread
From: Jens Axboe @ 2006-06-24 11:01 UTC (permalink / raw)
To: Fengguang Wu; +Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak
On Sat, Jun 24 2006, Fengguang Wu wrote:
> Introduce deadline_kick_page() to
> - find the request containing the page
> - remove its BIO_RW_AHEAD flag
> - reschedule if it was of type READA
>
> Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
> ---
>
>
> block/deadline-iosched.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
> 1 files changed, 43 insertions(+), 2 deletions(-)
>
> --- linux-2.6.17-rc6-mm2.orig/block/deadline-iosched.c
> +++ linux-2.6.17-rc6-mm2/block/deadline-iosched.c
> @@ -317,6 +317,44 @@ deadline_add_request(struct request_queu
> }
>
> /*
> + * We have a pending read on @page,
> + * find the corresponding request of type READA,
> + * promote it to READ, and reschedule it.
> + */
> +static int
> +deadline_kick_page(struct request_queue *q, struct page *page)
> +{
> + struct deadline_data *dd = q->elevator->elevator_data;
> + struct deadline_rq *drq;
> + struct request *rq;
> + struct list_head *pos;
> + struct bio_vec *bvec;
> + struct bio *bio;
> + int i;
> +
> + list_for_each(pos, &dd->fifo_list[READ]) {
> + drq = list_entry_fifo(pos);
> + rq = drq->request;
> + if (rq->flags & (1 << BIO_RW_AHEAD)) {
> + rq_for_each_bio(bio, rq) {
> + bio_for_each_segment(bvec, bio, i) {
> + if (page == bvec->bv_page)
> + goto found;
> + }
> + }
> + }
> + }
Uh that's horrible!
Before we go into further details, I'd like to see some numbers on where
this makes a difference.
--
Jens Axboe
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 7/7] iosched: introduce deadline_kick_page()
@ 2006-06-25 6:32 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-25 6:32 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak
On Sat, Jun 24, 2006 at 01:01:04PM +0200, Jens Axboe wrote:
> > /*
> > + * We have a pending read on @page,
> > + * find the corresponding request of type READA,
> > + * promote it to READ, and reschedule it.
> > + */
> > +static int
> > +deadline_kick_page(struct request_queue *q, struct page *page)
> > +{
> > + struct deadline_data *dd = q->elevator->elevator_data;
> > + struct deadline_rq *drq;
> > + struct request *rq;
> > + struct list_head *pos;
> > + struct bio_vec *bvec;
> > + struct bio *bio;
> > + int i;
> > +
> > + list_for_each(pos, &dd->fifo_list[READ]) {
> > + drq = list_entry_fifo(pos);
> > + rq = drq->request;
> > + if (rq->flags & (1 << BIO_RW_AHEAD)) {
> > + rq_for_each_bio(bio, rq) {
> > + bio_for_each_segment(bvec, bio, i) {
> > + if (page == bvec->bv_page)
> > + goto found;
> > + }
> > + }
> > + }
> > + }
>
> Uh that's horrible!
>
> Before we go into further details, I'd like to see some numbers on where
> this makes a difference.
Sorry, it is. It brings non-trivial overhead.
This is the oprofile outputs:
reading small files:
1245 c01edae4 9 0.1404 deadline_dispatch_requests
1253 c01ed4d6 9 0.1404 deadline_queue_empty
1338 c01ed3d5 8 0.1248 deadline_kick_page
1619 c01ed350 6 0.0936 deadline_add_drq_fifo
1707 c01eda62 5 0.0780 deadline_add_request
1712 c01ed2e5 5 0.0780 deadline_set_request
1867 c01ed871 4 0.0624 deadline_remove_request
2242 c01ed9b9 2 0.0312 deadline_add_drq_rb
2244 c01edc1e 2 0.0312 deadline_merge
2246 c01ed923 2 0.0312 deadline_move_request
2249 c01ed232 2 0.0312 deadline_put_request
reading a big file:
1330 c01ed3d5 89 0.2926 deadline_kick_page
2528 c01edae4 16 0.0526 deadline_dispatch_requests
3036 c01ed9b9 8 0.0263 deadline_add_drq_rb
3163 c01ed4d6 7 0.0230 deadline_queue_empty
3394 c01edc1e 5 0.0164 deadline_merge
3399 c01ed923 5 0.0164 deadline_move_request
3403 c01ed2e5 5 0.0164 deadline_set_request
3707 c01eda62 3 0.0099 deadline_add_request
3711 c01ed871 3 0.0099 deadline_remove_request
3917 c01ede3c 2 0.0066 deadline_merged_request
3920 c01ed232 2 0.0066 deadline_put_request
4214 c01ed350 1 0.0033 deadline_add_drq_fifo
The overhead of deadline_kick_page() becomes large when the request is
large (256 pages). But I guess there's way to optimize it:
- most requests will be consisted of a set of continuous pages, i.e. a
range comparison will be sufficient.
- for a system with lots of queued requests(>100), maybe the gain can
well pay for the overheads?
btw, some mails for this patchset did not return to me, perhaps my
mail system was broken after a previous crash... Sorry, I'll resend
them soon.
Thanks,
Wu
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 7/7] iosched: introduce deadline_kick_page()
@ 2006-06-25 6:32 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-06-25 6:32 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak
On Sat, Jun 24, 2006 at 01:01:04PM +0200, Jens Axboe wrote:
> > /*
> > + * We have a pending read on @page,
> > + * find the corresponding request of type READA,
> > + * promote it to READ, and reschedule it.
> > + */
> > +static int
> > +deadline_kick_page(struct request_queue *q, struct page *page)
> > +{
> > + struct deadline_data *dd = q->elevator->elevator_data;
> > + struct deadline_rq *drq;
> > + struct request *rq;
> > + struct list_head *pos;
> > + struct bio_vec *bvec;
> > + struct bio *bio;
> > + int i;
> > +
> > + list_for_each(pos, &dd->fifo_list[READ]) {
> > + drq = list_entry_fifo(pos);
> > + rq = drq->request;
> > + if (rq->flags & (1 << BIO_RW_AHEAD)) {
> > + rq_for_each_bio(bio, rq) {
> > + bio_for_each_segment(bvec, bio, i) {
> > + if (page == bvec->bv_page)
> > + goto found;
> > + }
> > + }
> > + }
> > + }
>
> Uh that's horrible!
>
> Before we go into further details, I'd like to see some numbers on where
> this makes a difference.
Sorry, it is. It brings non-trivial overhead.
This is the oprofile outputs:
reading small files:
1245 c01edae4 9 0.1404 deadline_dispatch_requests
1253 c01ed4d6 9 0.1404 deadline_queue_empty
1338 c01ed3d5 8 0.1248 deadline_kick_page
1619 c01ed350 6 0.0936 deadline_add_drq_fifo
1707 c01eda62 5 0.0780 deadline_add_request
1712 c01ed2e5 5 0.0780 deadline_set_request
1867 c01ed871 4 0.0624 deadline_remove_request
2242 c01ed9b9 2 0.0312 deadline_add_drq_rb
2244 c01edc1e 2 0.0312 deadline_merge
2246 c01ed923 2 0.0312 deadline_move_request
2249 c01ed232 2 0.0312 deadline_put_request
reading a big file:
1330 c01ed3d5 89 0.2926 deadline_kick_page
2528 c01edae4 16 0.0526 deadline_dispatch_requests
3036 c01ed9b9 8 0.0263 deadline_add_drq_rb
3163 c01ed4d6 7 0.0230 deadline_queue_empty
3394 c01edc1e 5 0.0164 deadline_merge
3399 c01ed923 5 0.0164 deadline_move_request
3403 c01ed2e5 5 0.0164 deadline_set_request
3707 c01eda62 3 0.0099 deadline_add_request
3711 c01ed871 3 0.0099 deadline_remove_request
3917 c01ede3c 2 0.0066 deadline_merged_request
3920 c01ed232 2 0.0066 deadline_put_request
4214 c01ed350 1 0.0033 deadline_add_drq_fifo
The overhead of deadline_kick_page() becomes large when the request is
large (256 pages). But I guess there's way to optimize it:
- most requests will be consisted of a set of continuous pages, i.e. a
range comparison will be sufficient.
- for a system with lots of queued requests(>100), maybe the gain can
well pay for the overheads?
btw, some mails for this patchset did not return to me, perhaps my
mail system was broken after a previous crash... Sorry, I'll resend
them soon.
Thanks,
Wu
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 7/7] iosched: introduce deadline_kick_page()
@ 2006-06-28 11:27 ` Jens Axboe
2006-07-04 1:32 ` Fengguang Wu
0 siblings, 1 reply; 11+ messages in thread
From: Jens Axboe @ 2006-06-28 11:27 UTC (permalink / raw)
To: Fengguang Wu, linux-kernel, Andrew Morton, Nick Piggin,
Lubos Lunak
On Sun, Jun 25 2006, Fengguang Wu wrote:
> On Sat, Jun 24, 2006 at 01:01:04PM +0200, Jens Axboe wrote:
> > > /*
> > > + * We have a pending read on @page,
> > > + * find the corresponding request of type READA,
> > > + * promote it to READ, and reschedule it.
> > > + */
> > > +static int
> > > +deadline_kick_page(struct request_queue *q, struct page *page)
> > > +{
> > > + struct deadline_data *dd = q->elevator->elevator_data;
> > > + struct deadline_rq *drq;
> > > + struct request *rq;
> > > + struct list_head *pos;
> > > + struct bio_vec *bvec;
> > > + struct bio *bio;
> > > + int i;
> > > +
> > > + list_for_each(pos, &dd->fifo_list[READ]) {
> > > + drq = list_entry_fifo(pos);
> > > + rq = drq->request;
> > > + if (rq->flags & (1 << BIO_RW_AHEAD)) {
> > > + rq_for_each_bio(bio, rq) {
> > > + bio_for_each_segment(bvec, bio, i) {
> > > + if (page == bvec->bv_page)
> > > + goto found;
> > > + }
> > > + }
> > > + }
> > > + }
> >
> > Uh that's horrible!
> >
> > Before we go into further details, I'd like to see some numbers on where
> > this makes a difference.
>
> Sorry, it is. It brings non-trivial overhead.
Sorry for the late reply, apparently spamassassin thought this was
spam...
> This is the oprofile outputs:
>
> reading small files:
> 1245 c01edae4 9 0.1404 deadline_dispatch_requests
> 1253 c01ed4d6 9 0.1404 deadline_queue_empty
> 1338 c01ed3d5 8 0.1248 deadline_kick_page
> 1619 c01ed350 6 0.0936 deadline_add_drq_fifo
> 1707 c01eda62 5 0.0780 deadline_add_request
> 1712 c01ed2e5 5 0.0780 deadline_set_request
> 1867 c01ed871 4 0.0624 deadline_remove_request
> 2242 c01ed9b9 2 0.0312 deadline_add_drq_rb
> 2244 c01edc1e 2 0.0312 deadline_merge
> 2246 c01ed923 2 0.0312 deadline_move_request
> 2249 c01ed232 2 0.0312 deadline_put_request
>
> reading a big file:
> 1330 c01ed3d5 89 0.2926 deadline_kick_page
> 2528 c01edae4 16 0.0526 deadline_dispatch_requests
> 3036 c01ed9b9 8 0.0263 deadline_add_drq_rb
> 3163 c01ed4d6 7 0.0230 deadline_queue_empty
> 3394 c01edc1e 5 0.0164 deadline_merge
> 3399 c01ed923 5 0.0164 deadline_move_request
> 3403 c01ed2e5 5 0.0164 deadline_set_request
> 3707 c01eda62 3 0.0099 deadline_add_request
> 3711 c01ed871 3 0.0099 deadline_remove_request
> 3917 c01ede3c 2 0.0066 deadline_merged_request
> 3920 c01ed232 2 0.0066 deadline_put_request
> 4214 c01ed350 1 0.0033 deadline_add_drq_fifo
>
> The overhead of deadline_kick_page() becomes large when the request is
> large (256 pages). But I guess there's way to optimize it:
> - most requests will be consisted of a set of continuous pages, i.e. a
> range comparison will be sufficient.
> - for a system with lots of queued requests(>100), maybe the gain can
> well pay for the overheads?
Sorry, there's just no way that something like that is acceptable for
inclusion. I don't care much about the overhead numbers (I can see from
the code that it sucks :-), I wanted to see some numbers on what
scenarios this helps performance and by how much.
--
Jens Axboe
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: [PATCH 7/7] iosched: introduce deadline_kick_page()
@ 2006-07-04 1:32 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-07-04 1:32 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak
Jens,
On Wed, Jun 28, 2006 at 01:27:32PM +0200, Jens Axboe wrote:
> > The overhead of deadline_kick_page() becomes large when the request is
> > large (256 pages). But I guess there's way to optimize it:
> > - most requests will be consisted of a set of continuous pages, i.e. a
> > range comparison will be sufficient.
> > - for a system with lots of queued requests(>100), maybe the gain can
> > well pay for the overheads?
>
> Sorry, there's just no way that something like that is acceptable for
> inclusion. I don't care much about the overhead numbers (I can see from
> the code that it sucks :-), I wanted to see some numbers on what
> scenarios this helps performance and by how much.
Ok, thanks. I hope that I'll be able to bring with some performance
numbers the next time :-)
Regards,
Wu
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 7/7] iosched: introduce deadline_kick_page()
@ 2006-07-04 1:32 ` Fengguang Wu
0 siblings, 0 replies; 11+ messages in thread
From: Fengguang Wu @ 2006-07-04 1:32 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-kernel, Andrew Morton, Nick Piggin, Lubos Lunak
Jens,
On Wed, Jun 28, 2006 at 01:27:32PM +0200, Jens Axboe wrote:
> > The overhead of deadline_kick_page() becomes large when the request is
> > large (256 pages). But I guess there's way to optimize it:
> > - most requests will be consisted of a set of continuous pages, i.e. a
> > range comparison will be sufficient.
> > - for a system with lots of queued requests(>100), maybe the gain can
> > well pay for the overheads?
>
> Sorry, there's just no way that something like that is acceptable for
> inclusion. I don't care much about the overhead numbers (I can see from
> the code that it sucks :-), I wanted to see some numbers on what
> scenarios this helps performance and by how much.
Ok, thanks. I hope that I'll be able to bring with some performance
numbers the next time :-)
Regards,
Wu
^ permalink raw reply [flat|nested] 11+ messages in thread