From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id F26F46B0044 for ; Mon, 21 Dec 2009 04:21:25 -0500 (EST) From: "Hiremath, Vaibhav" Date: Mon, 21 Dec 2009 14:51:13 +0530 Subject: RE: CPU consumption is going as high as 95% on ARM Cortex A8 Message-ID: <19F8576C6E063C45BE387C64729E73940449F43EEE@dbde02.ent.ti.com> References: <19F8576C6E063C45BE387C64729E73940449F43857@dbde02.ent.ti.com> <20091217095641.GA399@n2100.arm.linux.org.uk> <19F8576C6E063C45BE387C64729E73940449F43E29@dbde02.ent.ti.com> <20091221090750.GA11669@n2100.arm.linux.org.uk> In-Reply-To: <20091221090750.GA11669@n2100.arm.linux.org.uk> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org To: Russell King - ARM Linux Cc: "linux-arm-kernel@lists.infradead.org" , "linux-mm@kvack.org" , "linux-omap@vger.kernel.org" List-ID: > -----Original Message----- > From: Russell King - ARM Linux [mailto:linux@arm.linux.org.uk] > Sent: Monday, December 21, 2009 2:38 PM > To: Hiremath, Vaibhav > Cc: linux-arm-kernel@lists.infradead.org; linux-mm@kvack.org; linux- > omap@vger.kernel.org > Subject: Re: CPU consumption is going as high as 95% on ARM Cortex > A8 >=20 > On Mon, Dec 21, 2009 at 11:56:23AM +0530, Hiremath, Vaibhav wrote: > > > vma->vm_page_prot =3D pgprot_noncached(vma->vm_page_prot); > > > > > > will result in the memory being mapped as 'Strongly Ordered', > > > resulting > > > in there being multiple mappings with differing types. In later > > > kernels, we have pgprot_dmacoherent() and I'd suggest changing > the > > > above > > > macro for that. > > > > > > > I tried with your suggestion above but unfortunately it didn't > work for > > me. I am seeing the same behavior with the pgprot_dmacoherent(). I > > pulled your patch (which got applied cleanly on 2.6.32-rc5) - >=20 > What happens if you comment out the pgprot_dmacoherent() / > pgprot_noncached() > line completely? >=20 [Hiremath, Vaibhav] If I comment the line completely then I am seeing CPU c= onsumption similar to when I was setting PAGE_READONLY/PAGE_SHARED flag, wh= ich is 25-32%. Thanks, Vaibhav > I suspect that will "solve" the problem - but you'll then no longer > have > DMA coherency with userspace, so its not really a solution. -- 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