The patch titled
pktcdvd: bio write congestion using blk_congestion_wait()
has been added to the -mm tree. Its filename is
pktcdvd-bio-write-congestion-using-blk_congestion_wait.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: pktcdvd: bio write congestion using blk_congestion_wait()
From: "Thomas Maier" <balagi@xxxxxxxxxxx>
This adds a bio write queue congestion control to the pktcdvd driver with
fixed on/off marks. It prevents that the driver consumes a unlimited
amount of write requests.
Signed-off-by: Thomas Maier <balagi@xxxxxxxxxxx>
Cc: Peter Osterlund <petero2@xxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/block/pktcdvd.c | 32 ++++++++++++++++++++++++++++++++
include/linux/pktcdvd.h | 9 +++++++++
2 files changed, 41 insertions(+)
diff -puN drivers/block/pktcdvd.c~pktcdvd-bio-write-congestion-using-blk_congestion_wait drivers/block/pktcdvd.c
--- a/drivers/block/pktcdvd.c~pktcdvd-bio-write-congestion-using-blk_congestion_wait
+++ a/drivers/block/pktcdvd.c
@@ -83,6 +83,8 @@
static struct pktcdvd_device *pkt_devs[MAX_WRITERS];
static struct proc_dir_entry *pkt_proc;
static int pktdev_major;
+static int write_congestion_on = PKT_WRITE_CONGESTION_ON;
+static int write_congestion_off = PKT_WRITE_CONGESTION_OFF;
static struct mutex ctl_mutex; /* Serialize open/close/setup/teardown */
static mempool_t *psd_pool;
@@ -893,6 +895,7 @@ static int pkt_handle_queue(struct pktcd
sector_t zone = 0; /* Suppress gcc warning */
struct pkt_rb_node *node, *first_node;
struct rb_node *n;
+ int wakeup;
VPRINTK("handle_queue\n");
@@ -965,7 +968,13 @@ try_next_bio:
pkt->write_size += bio->bi_size / CD_FRAMESIZE;
spin_unlock(&pkt->lock);
}
+ /* check write congestion marks, and if bio_queue_size is
+ below, wake up any waiters */
+ wakeup = (pd->write_congestion_on > 0
+ && pd->bio_queue_size <= pd->write_congestion_off);
spin_unlock(&pd->lock);
+ if (wakeup)
+ blk_clear_queue_congested(pd->disk->queue, WRITE);
pkt->sleep_time = max(PACKET_WAIT_TIME, 1);
pkt_set_state(pkt, PACKET_WAITING_STATE);
@@ -2178,6 +2187,23 @@ static int pkt_make_request(request_queu
}
spin_unlock(&pd->cdrw.active_list_lock);
+ /*
+ * Test if there is enough room left in the bio work queue
+ * (queue size >= congestion on mark).
+ * If not, wait till the work queue size is below the congestion off mark.
+ */
+ spin_lock(&pd->lock);
+ if (pd->write_congestion_on > 0
+ && pd->bio_queue_size >= pd->write_congestion_on) {
+ blk_set_queue_congested(q, WRITE);
+ do {
+ spin_unlock(&pd->lock);
+ blk_congestion_wait(WRITE, HZ);
+ spin_lock(&pd->lock);
+ } while(pd->bio_queue_size > pd->write_congestion_off);
+ }
+ spin_unlock(&pd->lock);
+
/*
* No matching packet found. Store the bio in the work queue.
*/
@@ -2297,6 +2323,9 @@ static int pkt_seq_show(struct seq_file
seq_printf(m, "\tstate:\t\t\ti:%d ow:%d rw:%d ww:%d rec:%d fin:%d\n",
states[0], states[1], states[2], states[3], states[4], states[5]);
+ seq_printf(m, "\twrite congestion marks:\toff=%d on=%d\n",
+ pd->write_congestion_off,
+ pd->write_congestion_on);
return 0;
}
@@ -2461,6 +2490,9 @@ static int pkt_setup_dev(struct pkt_ctrl
if (!pd->rb_pool)
goto out_mem;
+ pd->write_congestion_on = write_congestion_on;
+ pd->write_congestion_off = write_congestion_off;
+
disk = alloc_disk(1);
if (!disk)
goto out_mem;
diff -puN include/linux/pktcdvd.h~pktcdvd-bio-write-congestion-using-blk_congestion_wait include/linux/pktcdvd.h
--- a/include/linux/pktcdvd.h~pktcdvd-bio-write-congestion-using-blk_congestion_wait
+++ a/include/linux/pktcdvd.h
@@ -112,6 +112,12 @@ struct pkt_ctrl_command {
#include <linux/completion.h>
#include <linux/cdrom.h>
+
+/* default bio write queue congestion marks */
+#define PKT_WRITE_CONGESTION_ON 10000
+#define PKT_WRITE_CONGESTION_OFF 9000
+
+
struct packet_settings
{
__u32 size; /* packet size in (512 byte) sectors */
@@ -271,6 +277,9 @@ struct pktcdvd_device
struct packet_iosched iosched;
struct gendisk *disk;
+
+ int write_congestion_off;
+ int write_congestion_on;
};
#endif /* __KERNEL__ */
_
Patches currently in -mm which might be from balagi@xxxxxxxxxxx are
export-clear_queue_congested-and-set_queue_congested.patch
pktcdvd-reusability-of-procfs-functions.patch
pktcdvd-make-procfs-interface-optional.patch
pktcdvd-bio-write-congestion-using-blk_congestion_wait.patch
-
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