On 04/18/2016 03:36 PM, Mike Snitzer wrote: > On Mon, Apr 18 2016 at 1:31am -0400, > Baolin Wang <baolin.wang@xxxxxxxxxx> wrote: > >> Hi Herbert, >> >> On 15 April 2016 at 21:48, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: >>> On Tue, Mar 15, 2016 at 03:47:58PM +0800, Baolin Wang wrote: >>>> Now some cipher hardware engines prefer to handle bulk block by merging requests >>>> to increase the block size and thus increase the hardware engine processing speed. >>>> >>>> This patchset introduces request bulk mode to help the crypto hardware drivers >>>> improve in efficiency. >>> >>> Could you please explain why this merging can't be done in dm-crypt >>> instead? >> >> We've tried to do this in dm-crypt, but it failed. >> The dm-crypt maintainer explained to me that I should optimize the >> driver, not add strange hw-dependent crypto modes to dm-crypt, this is >> not the first crypto accelerator that is just not suited for this kind >> of use. > > As a DM mainatiner my only contribution to this line of discussion was > relative to your proposal to train the dm-crypt target (which is > bio-based) to also provide request-based support, see: > https://www.redhat.com/archives/dm-devel/2015-November/msg00112.html > > But follow-up discussion occured, primarily with Milan Broz, which led > to this bulk mode support in the crypto layer. Pretty strange Milan > wasn't cc'd on your patchset posting (I've now cc'd him). My complaint was mainly that the proposed dmcrypt based version just did not work properly. https://lkml.org/lkml/2016/1/2/109 (I did not test the new version we are replying here. I wonder how the problem I mentioned is fixed though. Also see Mikulas' comments https://www.redhat.com/archives/dm-devel/2016-January/msg00145.html) Anyway, all this seems to optimize case for specific crypto hw, that is not able to perform optimally with pattern dmcrypt produces. I do not think dmcrypt should do optimizations for specific hw. But if we decide that it is needed there, it should not cause any performance or compatibility problems elsewhere... Milan -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
