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@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>