**diff options**

author | NeilBrown <neilb@suse.de> | 2009-05-07 12:49:35 +1000 |
---|---|---|

committer | NeilBrown <neilb@suse.de> | 2009-05-07 12:49:35 +1000 |

commit | dd71cf6b2773310b01c6fe6c773064c80fd2476b (patch) | |

tree | 33a4cc4fe4db45ec4f1a8f477bb294a0b685efa4 /drivers | |

parent | db305e507d554430a69ede901a6308e6ecb72349 (diff) | |

download | linux-stericsson-dd71cf6b2773310b01c6fe6c773064c80fd2476b.tar.gz |

md: tidy up status_resync to handle large arrays.

Two problems in status_resync.
1/ It still used Kilobytes as the basic block unit, while most code
now uses sectors uniformly.
2/ It doesn't allow for the possibility that max_sectors exceeds
the range of "unsigned long".
So
- change "max_blocks" to "max_sectors", and store sector numbers
in there and in 'resync'
- Make 'rt' a 'sector_t' so it can temporarily hold the number of
remaining sectors.
- use sector_div rather than normal division.
- change the magic '100' used to preserve precision to '32'.
+ making it a power of 2 makes division easier
+ it doesn't need to be as large as it was chosen when we averaged
speed over the entire run. Now we average speed over the last 30
seconds or so.
Reported-by: "Mario 'BitKoenig' Holbe" <Mario.Holbe@TU-Ilmenau.DE>
Signed-off-by: NeilBrown <neilb@suse.de>

Diffstat (limited to 'drivers')

-rw-r--r-- | drivers/md/md.c | 45 |

1 files changed, 28 insertions, 17 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c index 612343fdde94..5eb01a4d27ba 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -5705,37 +5705,38 @@ static void status_unused(struct seq_file *seq) static void status_resync(struct seq_file *seq, mddev_t * mddev) { - sector_t max_blocks, resync, res; - unsigned long dt, db, rt; + sector_t max_sectors, resync, res; + unsigned long dt, db; + sector_t rt; int scale; unsigned int per_milli; - resync = (mddev->curr_resync - atomic_read(&mddev->recovery_active))/2; + resync = mddev->curr_resync - atomic_read(&mddev->recovery_active); if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) - max_blocks = mddev->resync_max_sectors >> 1; + max_sectors = mddev->resync_max_sectors; else - max_blocks = mddev->dev_sectors / 2; + max_sectors = mddev->dev_sectors; /* * Should not happen. */ - if (!max_blocks) { + if (!max_sectors) { MD_BUG(); return; } /* Pick 'scale' such that (resync>>scale)*1000 will fit - * in a sector_t, and (max_blocks>>scale) will fit in a + * in a sector_t, and (max_sectors>>scale) will fit in a * u32, as those are the requirements for sector_div. * Thus 'scale' must be at least 10 */ scale = 10; if (sizeof(sector_t) > sizeof(unsigned long)) { - while ( max_blocks/2 > (1ULL<<(scale+32))) + while ( max_sectors/2 > (1ULL<<(scale+32))) scale++; } res = (resync>>scale)*1000; - sector_div(res, (u32)((max_blocks>>scale)+1)); + sector_div(res, (u32)((max_sectors>>scale)+1)); per_milli = res; { @@ -5756,25 +5757,35 @@ static void status_resync(struct seq_file *seq, mddev_t * mddev) (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ? "resync" : "recovery"))), per_milli/10, per_milli % 10, - (unsigned long long) resync, - (unsigned long long) max_blocks); + (unsigned long long) resync/2, + (unsigned long long) max_sectors/2); /* - * We do not want to overflow, so the order of operands and - * the * 100 / 100 trick are important. We do a +1 to be - * safe against division by zero. We only estimate anyway. - * * dt: time from mark until now * db: blocks written from mark until now * rt: remaining time + * + * rt is a sector_t, so could be 32bit or 64bit. + * So we divide before multiply in case it is 32bit and close + * to the limit. + * We scale the divisor (db) by 32 to avoid loosing precision + * near the end of resync when the number of remaining sectors + * is close to 'db'. + * We then divide rt by 32 after multiplying by db to compensate. + * The '+1' avoids division by zero if db is very small. */ dt = ((jiffies - mddev->resync_mark) / HZ); if (!dt) dt++; db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active)) - mddev->resync_mark_cnt; - rt = (dt * ((unsigned long)(max_blocks-resync) / (db/2/100+1)))/100; - seq_printf(seq, " finish=%lu.%lumin", rt / 60, (rt % 60)/6); + rt = max_sectors - resync; /* number of remaining sectors */ + sector_div(rt, db/32+1); + rt *= dt; + rt >>= 5; + + seq_printf(seq, " finish=%lu.%lumin", (unsigned long)rt / 60, + ((unsigned long)rt % 60)/6); seq_printf(seq, " speed=%ldK/sec", db/2/dt); } |