From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH] iommu/amd - Optimize PPR log handling Date: Tue, 29 May 2018 16:54:05 +0200 Message-ID: <20180529145405.GN18595@8bytes.org> References: <152668031618.108078.8188026193559324640.stgit@wsp141332wss.amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <152668031618.108078.8188026193559324640.stgit-ztPFugr8rmfEhiLOc2DLklaTQe2KTcn/@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Gary R Hook Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org Hey Gary, On Fri, May 18, 2018 at 04:51:56PM -0500, Gary R Hook wrote: > Improve the performance of the PPR log polling function (i.e. the > task of emptying the log) by minimizing MMIO operations and more > efficiently processing groups of log entries. Cache the head > pointer, as there's never a reason to read it. Ensure the head > pointer register is updated every so often, to inform the IOMMU > that space is available in the log. > > Finally, since a single pass may leave logged events unread, use > an outer loop to repeat until head has caught up to tail. > > Signed-off-by: Gary R Hook Do you have numbers for the performance improvement? How did you test this patch? Regards, Joerg