From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dennis Dalessandro Subject: Re: [PATCH 00/16] IB/hfi1: Add a page pinning cache for PSM sdma Date: Tue, 8 Mar 2016 19:21:58 -0500 Message-ID: <20160309002157.GA20105@phlsvsds.ph.intel.com> References: <20160308191210.30542.91885.stgit@scvm10.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Or Gerlitz Cc: Doug Ledford , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-rdma@vger.kernel.org On Tue, Mar 08, 2016 at 10:56:48PM +0200, Or Gerlitz wrote: >On Tue, Mar 8, 2016 at 9:14 PM, Dennis Dalessandro > wrote: > >> This patch series adds a performance improvement to user SDMA transfers from >> PSM applications by caching user buffer pages after pinning them. Subsequent >> uses of the same user buffer will not incur the cost of pinning the same pages >> again. Additionally, the cost of unpinning the same pages is avoided. Buffer >> pages are unpinned when the context is torn down or when the driver determines >> that the buffer should be evicted from the cache. Cache evictions happen when >> there is a request for a new, uncached buffer and the current size of the cache >> has reached a pre-defined limit. > >If indeed there's a need for such a pin down cache, it should have >been implemented in the IB core, b/c both the problem and the solution >are generic and have nothing to do with certain device driver. Since this is for psm it has nothing to do with the IB core. I fail to see what that would achieve. >The problem is that you are bypassing the IB core altogether with a >proprietary character device in the hfi1 driver which managed to snick >in even in the presence of reviewer comments during the submission. Yes there were reviewer comments, and the maintainer made a decision. I would also not call this proprietary. It is open source after all: See: https://github.com/01org/opa-psm2 -Denny -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html