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During a 'resync' or similar activity, md checks if the devices in the array are otherwise active and winds back resync activity when they are. This test in done in is_mddev_idle, and it is somewhat fragile - it sometimes thinks there is non-sync io when there isn't. The test compares the total sectors of io (disk_stat_read) with the sectors of resync io (disk->sync_io). This has problems because total sectors gets updated when a request completes, while resync io gets updated when the request is submitted. The time difference can cause large differenced between the two which do not actually imply non-resync activity. The test currently allows for some fuzz (+/- 4096) but there are some cases when it is not enough. The test currently looks for any (non-fuzz) difference, either positive or negative. This clearly is not needed. Any non-sync activity will cause the total sectors to grow faster than the sync_io count (never slower) so we only need to look for a positive differences. If we do this then the amount of in-flight sync io will never cause the appearance of non-sync IO. Once enough non-sync IO to worry about starts happening, resync will be slowed down and the measurements will thus be more precise (as there is less in-flight) and control of resync will still be suitably responsive. Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| raid6test | ||
| .gitignore | ||
| bitmap.c | ||
| dm-bio-list.h | ||
| dm-bio-record.h | ||
| dm-crypt.c | ||
| dm-delay.c | ||
| dm-emc.c | ||
| dm-exception-store.c | ||
| dm-hw-handler.c | ||
| dm-hw-handler.h | ||
| dm-io.c | ||
| dm-io.h | ||
| dm-ioctl.c | ||
| dm-linear.c | ||
| dm-log.c | ||
| dm-log.h | ||
| dm-mpath.c | ||
| dm-mpath.h | ||
| dm-path-selector.c | ||
| dm-path-selector.h | ||
| dm-raid1.c | ||
| dm-round-robin.c | ||
| dm-snap.c | ||
| dm-snap.h | ||
| dm-stripe.c | ||
| dm-table.c | ||
| dm-target.c | ||
| dm-zero.c | ||
| dm.c | ||
| dm.h | ||
| faulty.c | ||
| Kconfig | ||
| kcopyd.c | ||
| kcopyd.h | ||
| linear.c | ||
| Makefile | ||
| md.c | ||
| mktables.c | ||
| multipath.c | ||
| raid0.c | ||
| raid1.c | ||
| raid5.c | ||
| raid6.h | ||
| raid6algos.c | ||
| raid6altivec.uc | ||
| raid6int.uc | ||
| raid6mmx.c | ||
| raid6recov.c | ||
| raid6sse1.c | ||
| raid6sse2.c | ||
| raid6x86.h | ||
| raid10.c | ||
| unroll.pl | ||
| xor.c | ||