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authorThomas Maier <balagi@justmail.de>2006-12-08 02:36:11 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-08 08:28:38 -0800
commit0a0fc9601dd1024ec7171993bf075a789246e1ed (patch)
treec606a35beb9c56ccfeff57cb594e6a7e5b12a80c
parent2d4eeec563a0472b68de3597c17f2d3b11c49c00 (diff)
downloadlinux-0a0fc9601dd1024ec7171993bf075a789246e1ed.tar.bz2
[PATCH] pktcdvd: bio write congestion using congestion_wait()
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. [akpm@osdl.org: sync with congestion_wait() renaming] Signed-off-by: Thomas Maier <balagi@justmail.de> Cc: Peter Osterlund <petero2@telia.com> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/block/pktcdvd.c32
-rw-r--r--include/linux/pktcdvd.h9
2 files changed, 41 insertions, 0 deletions
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 7e7b892f621a..91fbe7fd6d0b 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -84,6 +84,8 @@
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;
@@ -894,6 +896,7 @@ static int pkt_handle_queue(struct pktcdvd_device *pd)
sector_t zone = 0; /* Suppress gcc warning */
struct pkt_rb_node *node, *first_node;
struct rb_node *n;
+ int wakeup;
VPRINTK("handle_queue\n");
@@ -966,7 +969,13 @@ 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);
@@ -2179,6 +2188,23 @@ static int pkt_make_request(request_queue_t *q, struct bio *bio)
}
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);
+ 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.
*/
@@ -2298,6 +2324,9 @@ static int pkt_seq_show(struct seq_file *m, void *p)
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;
}
@@ -2474,6 +2503,9 @@ static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev)
init_waitqueue_head(&pd->wqueue);
pd->bio_queue = RB_ROOT;
+ pd->write_congestion_on = write_congestion_on;
+ pd->write_congestion_off = write_congestion_off;
+
disk = alloc_disk(1);
if (!disk)
goto out_mem;
diff --git a/include/linux/pktcdvd.h b/include/linux/pktcdvd.h
index 8a94c717c266..9b1a185fb1e5 100644
--- a/include/linux/pktcdvd.h
+++ b/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__ */