From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 0/2] Introduce the request handling for dm-crypt Date: Fri, 13 Nov 2015 10:05:15 +0100 Message-ID: <4015766.7tjD0ocbRK@wuerfel> References: <20151112125901.GD27454@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Baolin Wang Cc: Jan Kara , Christoph Hellwig , axboe@kernel.dk, Alasdair G Kergon , Mike Snitzer , dm-devel@redhat.com, neilb@suse.com, tj@kernel.org, jmoyer@redhat.com, keith.busch@intel.com, bart.vanassche@sandisk.com, linux-raid@vger.kernel.org, Mark Brown , "Garg, Dinesh" , LKML List-Id: linux-raid.ids On Friday 13 November 2015 10:05:28 Baolin Wang wrote: > > Well, I did a simple test with dd reading, cause my engine limitation is 1M, > (1) so the time like below when handle 1M at one time. > 1048576 bytes (1.0 MB) copied, 0.0841235 s, 12.5 MB/s > 1048576 bytes (1.0 MB) copied, 0.0836294 s, 12.5 MB/s > 1048576 bytes (1.0 MB) copied, 0.0836526 s, 12.5 MB/s > > (2) These handle 64K at one time * 16 times > 1048576 bytes (1.0 MB) copied, 0.0937223 s, 11.2 MB/s > 1048576 bytes (1.0 MB) copied, 0.097205 s, 10.8 MB/s > 1048576 bytes (1.0 MB) copied, 0.0935884 s, 11.2 MB/s > > Here is a 10ms level difference, try to image if the hardware engine's > throughput is bigger than that. But like Jens said, we can measure it > by the performance data. The absolute numbers look really low. Does this include writing to a hard drive? That would certainly make the difference appear less significant. Could you try backing this with a ram disk backing for comparison, and also use 'time dd' to show the CPU utilization for all cases? For completeness, including cpu-only performance might also help put this into perspective. Arnd