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| author | Paul Clements <paul.clements@steeleye.com> | 2010-03-08 08:02:37 +0300 |
|---|---|---|
| committer | NeilBrown <neilb@suse.de> | 2010-05-18 09:27:46 +0400 |
| commit | 696fcd535b5a8cfc0617e9cf1d9d69a13895cc1e (patch) | |
| tree | b9f55833c83a41a6e047f0de82b17d9753ad0542 | |
| parent | ee8b81b03dffa1c0075553d01c557714aedb85a1 (diff) | |
| download | linux-696fcd535b5a8cfc0617e9cf1d9d69a13895cc1e.tar.xz | |
md: expose max value of behind writes counter
Keep track of the maximum number of concurrent write-behind requests
for an md array and exposed this number in sysfs at
md/bitmap/max_backlog_used
Writing any value to this file will clear it.
This allows userspace to be involved in tuning bitmap/backlog.
Signed-off-by: Paul Clements <paul.clements@steeleye.com>
Signed-off-by: NeilBrown <neilb@suse.de>
| -rw-r--r-- | drivers/md/bitmap.c | 29 | ||||
| -rw-r--r-- | drivers/md/bitmap.h | 1 |
2 files changed, 29 insertions, 1 deletions
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index 26ac8aad0b19..6279393db64d 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -1292,9 +1292,14 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect if (!bitmap) return 0; if (behind) { + int bw; atomic_inc(&bitmap->behind_writes); + bw = atomic_read(&bitmap->behind_writes); + if (bw > bitmap->behind_writes_used) + bitmap->behind_writes_used = bw; + PRINTK(KERN_DEBUG "inc write-behind count %d/%d\n", - atomic_read(&bitmap->behind_writes), bitmap->max_write_behind); + bw, bitmap->max_write_behind); } while (sectors) { @@ -2006,6 +2011,27 @@ static ssize_t can_clear_store(mddev_t *mddev, const char *buf, size_t len) static struct md_sysfs_entry bitmap_can_clear = __ATTR(can_clear, S_IRUGO|S_IWUSR, can_clear_show, can_clear_store); +static ssize_t +behind_writes_used_show(mddev_t *mddev, char *page) +{ + if (mddev->bitmap == NULL) + return sprintf(page, "0\n"); + return sprintf(page, "%lu\n", + mddev->bitmap->behind_writes_used); +} + +static ssize_t +behind_writes_used_reset(mddev_t *mddev, const char *buf, size_t len) +{ + if (mddev->bitmap) + mddev->bitmap->behind_writes_used = 0; + return len; +} + +static struct md_sysfs_entry max_backlog_used = +__ATTR(max_backlog_used, S_IRUGO | S_IWUSR, + behind_writes_used_show, behind_writes_used_reset); + static struct attribute *md_bitmap_attrs[] = { &bitmap_location.attr, &bitmap_timeout.attr, @@ -2013,6 +2039,7 @@ static struct attribute *md_bitmap_attrs[] = { &bitmap_chunksize.attr, &bitmap_metadata.attr, &bitmap_can_clear.attr, + &max_backlog_used.attr, NULL }; struct attribute_group md_bitmap_group = { diff --git a/drivers/md/bitmap.h b/drivers/md/bitmap.h index cb821d76d1b4..aa82b7caa85f 100644 --- a/drivers/md/bitmap.h +++ b/drivers/md/bitmap.h @@ -227,6 +227,7 @@ struct bitmap { int allclean; atomic_t behind_writes; + unsigned long behind_writes_used; /* highest actual value at runtime */ /* * the bitmap daemon - periodically wakes up and sweeps the bitmap |