On Tue, Jul 24, 2012 at 05:19:26PM +0200, Milan Broz wrote:
> I have no time to check it today but this must be fixed. Read-ahead
> is just stupid workaround...
>
> # echo "0">/sys/block/sdc/queue/rotational
> # hdparm -t /dev/mapper/sdc_null_crypt
> Timing buffered disk reads: 220 MB in 3.01 seconds = 73.07 MB/sec
>
> # echo "1">/sys/block/sdc/queue/rotational
> # hdparm -t /dev/mapper/sdc_null_crypt
> Timing buffered disk reads: 652 MB in 3.01 seconds = 216.75 MB/sec
>
> This SSD is quicker if set to rotational mode!
> (So it merges requests in fact.)
That didn't help for me, strangely.
gandalfthegreat:~# blockdev --setra 256 /dev/mapper/cryptroot
gandalfthegreat:~# reset_cache
gandalfthegreat:~# dd if=/dev/mapper/cryptroot of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 43.4968 s, 24.7 MB/s
gandalfthegreat:~# dmsetup ls | grep cryptroot
cryptroot (254:0)
gandalfthegreat:~# echo "1">/sys/block/dm-0/queue/rotational
gandalfthegreat:~# reset_cache
gandalfthegreat:~# dd if=/dev/mapper/cryptroot of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 42.9933 s, 25.0 MB/s
Marc
--
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
.... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/
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