From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Pyrgiotis Subject: Journal question Date: Mon, 24 Dec 2012 20:46:30 +0200 Message-ID: <50D8A306.8050109@cslab.ece.ntua.gr> References: <50D8961A.1010703@cslab.ece.ntua.gr> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50D8961A.1010703-Hpc4xzY4zrDSDkk6z29a7FAUjnlXr6A1@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-bcache@vger.kernel.org Hi Kent, I was reading the code documentation on your site, and I saw that you have written this: "... In the future, the journal will contain a strong checksum of the data so that the write will complete when the journal entry finishes..." My question is, is this feature implemented? As far as I can see by looking at journal.c, you are journaling only the keys and not the data they point to (it has been issued asynchronously a few steps back to the SSD, right?). Also, if this is a feature to be implemented, wouldn't it create more stress on the CPUs, as well as more latency to issue the IO request to the SSDs (unless you issue it asynchronously while processing the keylist)? I'm just curious on how you'd handle it. Thanks, Alex