From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Tripathy Subject: Re: Block Size for Windows Date: Tue, 28 Aug 2012 23:43:47 +0100 Message-ID: <503D49A3.4090100@abpni.co.uk> References: <503BC71A.6050207@abpni.co.uk> <503BC82F.1030107@abpni.co.uk> <503BC897.3020606@abpni.co.uk> <503BCDC6.9010807@abpni.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kent Overstreet Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-bcache@vger.kernel.org On 27/08/2012 20:55, Kent Overstreet wrote: > On Mon, Aug 27, 2012 at 12:43 PM, Jonathan Tripathy wrote: >> On 27/08/2012 20:22, Kent Overstreet wrote: >>> echo 1 > /sys/fs/bcache//unregister >>> >>> echo 1 > /sys/block/bcache0/bcache/stop >> Ok, so I managed to recreate everything with a block size of 512 bytes. >> However, 2 bad things have happened: >> >> 1) In my Linux DomU, my fio randomwrite test have gone from about 28k iops >> to about 800 iops. Can this be fixed? changing bs and ba to 512 in the fio >> config file didn't hep. > Ouch! > > Bet the ssd doesn't like those 512 byte journal writes. I'm going to > have to think about that... Hi Kent, Ok, a little good news. I managed to sort out the low IOPS issue. When I formatted bcache0 with a 512 block size, I forgot to set the caching mode back to writeback. Once I did that, the IOPS were nice and high again (circa 26k IOPS). Sorry about the noise regarding that non-issue. I re-tried the windows setup with writeback enabled for the 512B formatted cache. It kernel paniced as per-usual, however for some reason, it's kernel panicking upon every boot now, whereas when it was formatted with 4k sectors, once the system came back up, it was stable (until I tried another windows setup). The debug trace appears to be the same as the one I posted to the list (kernel BUG at fs/bio.c:420! invalid opcode: 0000 [#1] SMP). I appreciate your time. Thanks