From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f181.google.com (mail-ig0-f181.google.com [209.85.213.181]) by kanga.kvack.org (Postfix) with ESMTP id B1FAA6B0031 for ; Wed, 25 Jun 2014 12:50:45 -0400 (EDT) Received: by mail-ig0-f181.google.com with SMTP id h15so1968495igd.2 for ; Wed, 25 Jun 2014 09:50:45 -0700 (PDT) Received: from cam-admin0.cambridge.arm.com (cam-admin0.cambridge.arm.com. [217.140.96.50]) by mx.google.com with ESMTP id q6si1897109igr.54.2014.06.25.09.50.44 for ; Wed, 25 Jun 2014 09:50:44 -0700 (PDT) Date: Wed, 25 Jun 2014 17:50:03 +0100 From: Mark Rutland Subject: Re: [PATCH 6/6] arm64: mm: Enable RCU fast_gup Message-ID: <20140625165003.GI15240@leverpostej> References: <1403710824-24340-1-git-send-email-steve.capper@linaro.org> <1403710824-24340-7-git-send-email-steve.capper@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1403710824-24340-7-git-send-email-steve.capper@linaro.org> Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: Steve Capper Cc: "linux-arm-kernel@lists.infradead.org" , Catalin Marinas , "linux@arm.linux.org.uk" , "linux-arch@vger.kernel.org" , "linux-mm@kvack.org" , "anders.roxell@linaro.org" , "peterz@infradead.org" , "gary.robertson@linaro.org" , Will Deacon , "akpm@linux-foundation.org" , "christoffer.dall@linaro.org" Hi Steve, On Wed, Jun 25, 2014 at 04:40:24PM +0100, Steve Capper wrote: > Activate the RCU fast_gup for ARM64. We also need to force THP splits > to broadcast an IPI s.t. we block in the fast_gup page walker. As THP > splits are comparatively rare, this should not lead to a noticeable > performance degradation. > > Some pre-requisite functions pud_write and pud_page are also added. > > Signed-off-by: Steve Capper > --- > arch/arm64/Kconfig | 3 +++ > arch/arm64/include/asm/pgtable.h | 11 ++++++++++- > arch/arm64/mm/flush.c | 19 +++++++++++++++++++ > 3 files changed, 32 insertions(+), 1 deletion(-) [...] > diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c > index e4193e3..ddf96c1 100644 > --- a/arch/arm64/mm/flush.c > +++ b/arch/arm64/mm/flush.c > @@ -103,3 +103,22 @@ EXPORT_SYMBOL(flush_dcache_page); > */ > EXPORT_SYMBOL(flush_cache_all); > EXPORT_SYMBOL(flush_icache_range); > + > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > +#ifdef CONFIG_HAVE_RCU_TABLE_FREE > +static void thp_splitting_flush_sync(void *arg) > +{ > +} > + > +void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, > + pmd_t *pmdp) > +{ > + pmd_t pmd = pmd_mksplitting(*pmdp); > + VM_BUG_ON(address & ~PMD_MASK); > + set_pmd_at(vma->vm_mm, address, pmdp, pmd); > + > + /* dummy IPI to serialise against fast_gup */ > + smp_call_function(thp_splitting_flush_sync, NULL, 1); Is there some reason we can't use kick_all_cpus_sync()? >>From a glance it seems that powerpc does just that. Mark. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org