From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Zwisler Subject: Re: [PATCH 1/7] Revert "mm: take i_mmap_lock in unmap_mapping_range() for DAX" Date: Thu, 1 Oct 2015 16:45:04 -0600 Message-ID: <20151001224504.GA7634@linux.intel.com> References: <1443685599-4843-1-git-send-email-david@fromorbit.com> <1443685599-4843-2-git-send-email-david@fromorbit.com> <20151001202729.GA23495@linux.intel.com> <1443737659.4886.3.camel@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "jack@suse.cz" , "linux-nvdimm@lists.01.org" , "dave.hansen@linux.intel.com" , "linux-kernel@vger.kernel.org" , "xfs@oss.sgi.com" , "linux-fsdevel@vger.kernel.org" , "willy@linux.intel.com" , "ross.zwisler@linux.intel.com" , "kirill.shutemov@linux.intel.com" To: "Williams, Dan J" Return-path: Content-Disposition: inline In-Reply-To: <1443737659.4886.3.camel@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com List-Id: linux-fsdevel.vger.kernel.org On Thu, Oct 01, 2015 at 10:14:22PM +0000, Williams, Dan J wrote: > Subject: pmem, dax: clean up clear_pmem() > > From: Dan Williams > > Both, __dax_pmd_fault, and clear_pmem() were taking special steps to > clear memory a page at a time to take advantage of non-temporal > clear_page() implementations. However, x86_64 does not use > non-temporal instructions for clear_page(), and arch_clear_pmem() was > always incurring the cost of __arch_wb_cache_pmem(). > > Clean up the assumption that doing clear_pmem() a page at a time is more > performant. > > Cc: Ross Zwisler > Reported-by: Dave Hansen > Signed-off-by: Dan Williams > --- > arch/x86/include/asm/pmem.h | 7 +------ > fs/dax.c | 4 +--- > 2 files changed, 2 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h > index d8ce3ec816ab..1544fabcd7f9 100644 > --- a/arch/x86/include/asm/pmem.h > +++ b/arch/x86/include/asm/pmem.h > @@ -132,12 +132,7 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size) > { > void *vaddr = (void __force *)addr; > > - /* TODO: implement the zeroing via non-temporal writes */ > - if (size == PAGE_SIZE && ((unsigned long)vaddr & ~PAGE_MASK) == 0) > - clear_page(vaddr); > - else > - memset(vaddr, 0, size); > - > + memset(vaddr, 0, size); > __arch_wb_cache_pmem(vaddr, size); > } > > diff --git a/fs/dax.c b/fs/dax.c > index b36d6d2e7f87..3faff9227135 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -625,9 +625,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, > goto fallback; > > if (buffer_unwritten(&bh) || buffer_new(&bh)) { > - int i; > - for (i = 0; i < PTRS_PER_PMD; i++) > - clear_page(kaddr + i * PAGE_SIZE); > + clear_pmem(kaddr, HPAGE_SIZE); > count_vm_event(PGMAJFAULT); > mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); > result |= VM_FAULT_MAJOR; > This clear_pmem() needs a wmb_pmem() after it. I'll make a quick series with the clean revert and this guy at the end and try and get them in v4.3 - sound good? _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs