From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id A4DBA1A0205 for ; Sat, 20 Sep 2014 06:57:05 +1000 (EST) Message-ID: <1411157986.13320.75.camel@snotra.buserror.net> Subject: Re: [PATCH 03/15] powerpc/msi: Improve IRQ bitmap allocator From: Scott Wood To: Michael Neuling Date: Fri, 19 Sep 2014 15:19:46 -0500 In-Reply-To: <1411157769.13320.74.camel@snotra.buserror.net> References: <1411028820-29933-1-git-send-email-mikey@neuling.org> <1411028820-29933-4-git-send-email-mikey@neuling.org> <1411157769.13320.74.camel@snotra.buserror.net> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Cc: cbe-oss-dev@lists.ozlabs.org, arnd@arndb.de, greg@kroah.com, imunsie@au.ibm.com, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Laurentiu Tudor , anton@samba.org, jk@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2014-09-19 at 15:16 -0500, Scott Wood wrote: > On Thu, 2014-09-18 at 18:26 +1000, Michael Neuling wrote: > > From: Ian Munsie > > > > Currently msi_bitmap_alloc_hwirqs() will round up any IRQ allocation requests > > to the nearest power of 2. eg. ask for 5 IRQs and you'll get 8. This wastes a > > lot of IRQs which can be a scarce resource. > > > > For cxl we can require multiple IRQs for every contexts that is attached to the > > accelerator. For AFU directed accelerators, there may be 1000s of contexts > > attached, hence we can easily run out of IRQs, especially if we are needlessly > > wasting them. > > > > This changes the msi_bitmap_alloc_hwirqs() to allocate only the required number > > of IRQs, hence avoiding this wastage. > > > > Signed-off-by: Ian Munsie > > Signed-off-by: Michael Neuling > > --- > > arch/powerpc/sysdev/msi_bitmap.c | 18 +++++++++++++----- > > 1 file changed, 13 insertions(+), 5 deletions(-) > > This conflicts with (and partially duplicates) > http://patchwork.ozlabs.org/patch/381892/ > which I have in my tree. How should we handle it? > > Laurentiu, from looking at the overlap between patches I see a problem > with your existing patch, regarding the out-of-irqs path and > msi_bitmap_free_hwirqs(), so one way or another that needs to get fixed > soon. Given the problems with Laurentiu's patch, perhaps it'd be best for me to just revert that patch in my tree, and respin it after this patchset has been merged. -Scott