Lower SSD-performance in 4.10 than in 4.9 kernel

Lower SSD-performance in 4.10 than in 4.9 kernel

[Joe Tienock]

Dear maintainers:

Let me please at first thank you for your work! I've been a linux enthusiast since about 1995 and this is the first time I have to report a possible bug to the kernel team. I'll keep it short to hopefully not cost you much time, and wait for further instructions.

Problem: SSD performance on same system changes drastically from using kernel 4.9.255 and older to using kernel 4.10.0-rc1 and newer, according to hdparm:

`linux@linux`:~$ uname -r
4.9.255-0409255-generic
`linux@linux`:~$ hdparm -Ttv /dev/sda
[...]
Timing buffered disk reads: 1432 MB in  3.00 seconds = 476.88 MB/sec

`linux@linux:`~$ uname -r
4.10.0-041000rc1-generic
`linux@linux`:~$ hdparm -Ttv /dev/sda
[...]
Timing buffered disk reads: 1140 MB in  3.00 seconds = 379.78 MB/sec

`linux@linux`:~$ uname -r
5.10.12
`linux@linux`:~$ sudo hdparm -Ttv /dev/sda
[...]
Timing buffered disk reads: 1138 MB in  3.01 seconds = 378.64 MB/sec

`linux@linux:~$ lspci -nnk``SATA controller [0106]: Intel Corporation 6 Series/C200 Series Chipset Family 6 port Mobile SATA AHCI Controller [8086:1c03] (rev 04)`
`Subsystem: Lenovo ThinkPad T520 [17aa:21cf]`
`Kernel driver in use: ahci`
`Kernel modules: ahci`

`linux@linux:~$` smartctl -d ata -x /dev/sda

Model Family:     Crucial/Micron BX/MX1/2/3/500, M5/600, 1100 SSDs
Device Model:     Crucial_CT525MX300SSD1
Firmware Version: M0CR070
User Capacity:    525.112.713.216 bytes [525 GB]
ATA Version is:   ACS-3 T13/2161-D revision 5
SATA Version is:  SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)

Any help would be highly appreciated!
Thanks in advance,
Joe