Commit 0a0fc960 authored by Thomas Maier's avatar Thomas Maier Committed by Linus Torvalds
Browse files

[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: default avatarThomas Maier <balagi@justmail.de>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2d4eeec5
......@@ -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 @@ static int pkt_handle_queue(struct pktcdvd_device *pd)
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;
......
......@@ -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__ */
......
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