Re: [PATCH #upstream-fixes] sata_mv: don't issue two DMA commands concurrently

[Artem Bokhan <aptem@ngs.ru>]

Now I spend ~1.9 seconds to serve one bad sector. That's great.
0.75 of 1.9 seconds is a time spent on hard reset, 1.15 seconds are 
spent on reallocation try.
Is hard reset real necessary to return disk to life after media error?



time dd if=/dev/sda of=/dev/null count=1 skip=300000
dd: reading `/dev/sda': Input/output error
0+0 records in
0+0 records out
0 bytes (0 B) copied, 1.87432 s, 0.0 kB/s

real    0m1.876s

[63107.038255] ata6.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x6
[63107.038287] ata6.00: edma_err_cause=00000084 pp_flags=00000003, dev 
error, EDMA self-disable
[63107.038335] ata6.00: cmd 60/08:00:e0:93:04/00:00:00:00:00/40 tag 0 
ncq 4096 in
[63107.038336]          res 51/40:08:e0:93:04/01:00:00:00:00/00 Emask 
0x409 (media error) <F>
[63107.038380] ata6.00: status: { DRDY ERR }
[63107.038403] ata6.00: error: { UNC }
[63107.038430] ata6: hard resetting link
[63107.608304] ata6: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[63107.692432] ata6.00: max_sectors limited to 256 for NCQ
[63107.772479] ata6.00: max_sectors limited to 256 for NCQ
[63107.772481] ata6.00: configured for UDMA/133
[63107.772488] sd 5:0:0:0: [sda] Result: hostbyte=DID_OK 
driverbyte=DRIVER_SENSE,SUGGEST_OK
[63107.772491] sd 5:0:0:0: [sda] Sense Key : Medium Error [current] 
[descriptor]
[63107.772495] Descriptor sense data with sense descriptors (in hex):
[63107.772497]         72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
[63107.772504]         00 04 93 e0
[63107.772507] sd 5:0:0:0: [sda] Add. Sense: Unrecovered read error - 
auto reallocate failed
[63107.772512] end_request: I/O error, dev sda, sector 300000
[63107.772540] Buffer I/O error on device sda, logical block 37500
[63107.772572] ata6: EH complete
[63107.790290] sd 5:0:0:0: [sda] 1465149168 512-byte hardware sectors 
(750156 MB)
[63107.790290] sd 5:0:0:0: [sda] Write Protect is off
[63107.790290] sd 5:0:0:0: [sda] Mode Sense: 00 3a 00 00
[63107.790290] sd 5:0:0:0: [sda] Write cache: enabled, read cache: 
enabled, doesn't support DPO or FUA




Mark Lord пишет:
> Artem Bokhan wrote:
> ..
>> IMHO, looks like cavity somewhere... Any ideas?
> ..
>
> Have you tried to disable fs read-ahead?
>
> Something like "hdparm -a0 /dev/sd*" ?
>
> -ml