Re: Stop SSD from waiting for "Spinning up disk..."

[Jeff Chua]

On Wed, Jun 24, 2015 at 2:55 AM, Martin Steigerwald <martin@xxxxxxxxxxxx> wrote:
> Am Dienstag, 23. Juni 2015, 20:26:12 schriebst Du:
>> Hi,
>
> Hi,
>
>> [proper In-Reply-To trail missing since lkml.org now fails to provide it]
> [â]
>> > Greg,
>> >
>> > SSD is coming mainstream and it doesn't make sense wasting time
>> > spinning up "disk" ...
>>
>> ...which probably is not truly being achieved
>> by providing a *custom* kernel parameter
>> which does apply to only those disk instances
>> which some users *specifically* care about.
>>
>> Some things come to mind:
>>
>> - at this scope, generally spoken
>>   one shouldn't be concerned with whether "we are SSD",
>>   but rather whether "we (do not) need spinup"
>>   (which might apply to a ton of different SCSI-based storage devices,
>>   even some SAN-based platter-based ones)
>>   *This* is what this is about
>>   (and this could then have been reflected in kernel parameter naming)
> [â]
>> - the kernel must already have some mechanisms to discern between
>> (non-)platters (e.g. perhaps for knowing whether to support SSD TRIM
>> command)
>
> Yep, for the first SSD in this laptop:
>
> merkaba:/sys> cat
> ./devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sda/queue/rotational
> 0


It seems "rotational" is not reporting the correct status on USB devices ...

# cat /sys/devices/pci0000:00/0000:00:1f.2/ata1/host0/target0:0:0/0:0:0:0/block/sda/queue/rotational
0
# cat sys/devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1:1.0/host10/target10:0:0/10:0:0:0/block/sdb/queue/rotational
1

# dmesg
scsi host11: uas
scsi 10:0:0:0: Direct-Access     JMicron  Generic          0114 PQ: 0 ANSI: 6

# cat /sys/kernel/debug/usb/devices
T:  Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  4 Spd=5000 MxCh= 0
D:  Ver= 3.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 9 #Cfgs=  1
P:  Vendor=152d ProdID=0567 Rev= 1.14
S:  Manufacturer=JMicron
S:  Product=USB to ATA/ATAPI Bridge
S:  SerialNumber=3186E514500030
C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=  8mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=uas


Both sda and sdb have the same SSD model.


Jeff
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