From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f52.google.com (mail-pa0-f52.google.com [209.85.220.52]) by kanga.kvack.org (Postfix) with ESMTP id A0CE0900016 for ; Tue, 2 Jun 2015 15:06:29 -0400 (EDT) Received: by pabqy3 with SMTP id qy3so18414310pab.3 for ; Tue, 02 Jun 2015 12:06:29 -0700 (PDT) Received: from g1t5425.austin.hp.com (g1t5425.austin.hp.com. [15.216.225.55]) by mx.google.com with ESMTPS id m6si27613852pdr.252.2015.06.02.12.06.28 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 02 Jun 2015 12:06:28 -0700 (PDT) Message-ID: <1433270808.23540.155.camel@misato.fc.hp.com> Subject: Re: [PATCH v12 0/10] Support Write-Through mapping on x86 From: Toshi Kani Date: Tue, 02 Jun 2015 12:46:48 -0600 In-Reply-To: <20150602162103.GL23057@wotan.suse.de> References: <1433187393-22688-1-git-send-email-toshi.kani@hp.com> <20150602162103.GL23057@wotan.suse.de> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Luis R. Rodriguez" Cc: bp@alien8.de, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-nvdimm@lists.01.org, jgross@suse.com, stefan.bader@canonical.com, luto@amacapital.net, hmh@hmh.eng.br, yigal@plexistor.com, konrad.wilk@oracle.com, Elliott@hp.com, hch@lst.de On Tue, 2015-06-02 at 18:21 +0200, Luis R. Rodriguez wrote: > On Mon, Jun 01, 2015 at 01:36:23PM -0600, Toshi Kani wrote: > > This patchset adds support of Write-Through (WT) mapping on x86. > > The study below shows that using WT mapping may be useful for > > non-volatile memory. > > > > http://www.hpl.hp.com/techreports/2012/HPL-2012-236.pdf > > > > The patchset consists of the following changes. > > - Patch 1/10 to 6/10 add ioremap_wt() > > - Patch 7/10 adds pgprot_writethrough() > > - Patch 8/10 to 9/10 add set_memory_wt() > > - Patch 10/10 changes the pmem driver to call ioremap_wt() > > > > All new/modified interfaces have been tested. > > > > The patchset is based on: > > git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git#tip-mm-2 > > While at it can you also look at: > > mcgrof@ergon ~/linux-next (git::master)$ git grep -4 "writethrough" drivers/infiniband/ Thanks for checking this. The inifiniband driver uses WT mappings on powerpc without proper WT interfaces defined. They can be cleaned up by a separate patch series to support WT on powerpc in the same way after this patchset (support WT on x86) is settled. > drivers/infiniband/hw/ipath/ipath_driver.c- > drivers/infiniband/hw/ipath/ipath_driver.c- dd->ipath_pcirev = pdev->revision; > drivers/infiniband/hw/ipath/ipath_driver.c- > drivers/infiniband/hw/ipath/ipath_driver.c-#if defined(__powerpc__) > drivers/infiniband/hw/ipath/ipath_driver.c: /* There isn't a generic way to specify writethrough mappings */ > drivers/infiniband/hw/ipath/ipath_driver.c- dd->ipath_kregbase = __ioremap(addr, len, > drivers/infiniband/hw/ipath/ipath_driver.c- (_PAGE_NO_CACHE|_PAGE_WRITETHRU)); > drivers/infiniband/hw/ipath/ipath_driver.c-#else > drivers/infiniband/hw/ipath/ipath_driver.c- dd->ipath_kregbase = ioremap_nocache(addr, len); Once powerpc defines ioremap_wt(), this driver can simply call ioremap_wt() without the ifdef. ioremap_wt() is defined as ioremap_nocache() on the architectures without WT support. > drivers/infiniband/hw/ipath/ipath_file_ops.c- > drivers/infiniband/hw/ipath/ipath_file_ops.c- phys = dd->ipath_physaddr + piobufs; > drivers/infiniband/hw/ipath/ipath_file_ops.c- > drivers/infiniband/hw/ipath/ipath_file_ops.c-#if defined(__powerpc__) > drivers/infiniband/hw/ipath/ipath_file_ops.c: /* There isn't a generic way to specify writethrough mappings */ > drivers/infiniband/hw/ipath/ipath_file_ops.c- pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE; > drivers/infiniband/hw/ipath/ipath_file_ops.c- pgprot_val(vma->vm_page_prot) |= _PAGE_WRITETHRU; > drivers/infiniband/hw/ipath/ipath_file_ops.c- pgprot_val(vma->vm_page_prot) &= ~_PAGE_GUARDED; > drivers/infiniband/hw/ipath/ipath_file_ops.c-#endif Once powerpc defines pgprot_writethrough(), this driver can use it without the ifdef. pgprot_writethrough() is defined as pgprot_noncached() on the architectures without WT support. > drivers/infiniband/hw/qib/qib_file_ops.c- > drivers/infiniband/hw/qib/qib_file_ops.c- phys = dd->physaddr + piobufs; > drivers/infiniband/hw/qib/qib_file_ops.c- > drivers/infiniband/hw/qib/qib_file_ops.c-#if defined(__powerpc__) > drivers/infiniband/hw/qib/qib_file_ops.c: /* There isn't a generic way to specify writethrough mappings */ > drivers/infiniband/hw/qib/qib_file_ops.c- pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE; > drivers/infiniband/hw/qib/qib_file_ops.c- pgprot_val(vma->vm_page_prot) |= _PAGE_WRITETHRU; > drivers/infiniband/hw/qib/qib_file_ops.c- pgprot_val(vma->vm_page_prot) &= ~_PAGE_GUARDED; > drivers/infiniband/hw/qib/qib_file_ops.c-#endif Same as above. > drivers/infiniband/hw/qib/qib_pcie.c- addr = pci_resource_start(pdev, 0); > drivers/infiniband/hw/qib/qib_pcie.c- len = pci_resource_len(pdev, 0); > drivers/infiniband/hw/qib/qib_pcie.c- > drivers/infiniband/hw/qib/qib_pcie.c-#if defined(__powerpc__) > drivers/infiniband/hw/qib/qib_pcie.c: /* There isn't a generic way to specify writethrough mappings */ > drivers/infiniband/hw/qib/qib_pcie.c- dd->kregbase = __ioremap(addr, len, _PAGE_NO_CACHE | _PAGE_WRITETHRU); > drivers/infiniband/hw/qib/qib_pcie.c-#else > drivers/infiniband/hw/qib/qib_pcie.c- dd->kregbase = ioremap_nocache(addr, len); > drivers/infiniband/hw/qib/qib_pcie.c-#endif Same as ipath_driver.c. Thanks, -Toshi -- 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