On 07/24/2012 05:02 PM, Marc MERLIN wrote: > On Tue, Jul 24, 2012 at 08:25:18AM +0200, Heinz Diehl wrote: >> Please correct me if I should be wrong, but your drive should report >> 512/4096 here, so it lies about the real blocksize it uses (4k). >> This raises the question if you have created your filesystem on top of >> the encrypted partition with e.g. "-b 4096". > > I'm using btrfs, which defaults to 4K blocks. Also, I was I seeing 270MB/s > reading a big file with btrfs on top of cryptroot. > > On Tue, Jul 24, 2012 at 10:44:36AM +0200, Milan Broz wrote: >> Seems I am running out of ideas :) >> (I just read the mails again and I think I am missing something >> obvious. Whatever, I will return to it later.) > > I wanted to command you for not giving up, you definitely went the extra > mile :) :) So seems elevator completely misbehaves for SSD in some situations. 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.) Milan _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
