From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: Quick bcache benchmark Date: Fri, 9 Dec 2011 22:33:23 -0800 Message-ID: <20111210063307.GA16262@moria> References: <20111206082233.GA19390@moria> <20111206115617.GA32759@moria> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Marcus Sorensen Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-bcache@vger.kernel.org On Fri, Dec 09, 2011 at 10:09:55AM -0700, Marcus Sorensen wrote: > Here's some more info. I'm running kernel 3.1.4. When I do random > writes, the 'bypassed' number increases in stats. Now I'm random > writing direct to /dev/bcache0 and get the same result. Weird. From what you're describing it sounds like throttling is screwed up (and it was recently), but I can't reproduce it now. Can you try echoing 0 to congested_threshold_us in the cache set dir, and seeing if that fixes it? > There also seems to be some work needed with clean-up, since I'm > unfamiliar with how bcache works I attempted to make-bcache twice, > thinking I'd start over. That worked, but because my cache device was > already registered I was unable to re-register my newly formatted > cache dev, got "kobject_add_internal failed for bcache with -EEXIST, > don't try to register things with the same name in the same > directory." I was still able to use my cache device via the old uuid, > but this will probably cause problems on reboot. Perhaps an unregister > file in /sys/fs/bcache would help, I also tried rmmod'ing bcache to > see if I could clear /sys/fs/bcache, but no luck. make-bcache should > perhaps check for an existing superblock, ask for confirmation, and > give some sort instruction on how to unregister, or do it for you if > you reformat. Yeah, I think for some reason bcache isn't opening the devices exclusively on 3.1. I'll have a look...