From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Kirill A. Shutemov" Subject: Re: [PATCH V4 0/2] mm: FAULT_AROUND_ORDER patchset performance data for powerpc Date: Tue, 27 May 2014 13:21:59 +0300 (EEST) Message-ID: <20140527102200.012BBE009B@blue.fi.intel.com> References: <1399541296-18810-1-git-send-email-maddy@linux.vnet.ibm.com> <537479E7.90806@linux.vnet.ibm.com> <87wqdik4n5.fsf@rustcorp.com.au> <53797511.1050409@linux.vnet.ibm.com> <20140519164301.eafd3dd288ccb88361ddcfc7@linux-foundation.org> <20140520004429.E660AE009B@blue.fi.intel.com> <87oaythsvk.fsf@rustcorp.com.au> <20140520102738.7F096E009B@blue.fi.intel.com> <53842FB1.7090909@linux.vnet.ibm.com> Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53842FB1.7090909@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org To: Madhavan Srinivasan Cc: "Kirill A. Shutemov" , Rusty Russell , Andrew Morton , Hugh Dickins , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, x86@kernel.org, benh@kernel.crashing.org, paulus@samba.org, riel@redhat.com, mgorman@suse.de, ak@linux.intel.com, peterz@infradead.org, mingo@kernel.org, dave.hansen@intel.com List-Id: linux-arch.vger.kernel.org Madhavan Srinivasan wrote: > On Tuesday 20 May 2014 03:57 PM, Kirill A. Shutemov wrote: > > Rusty Russell wrote: > >> "Kirill A. Shutemov" writes: > >>> Andrew Morton wrote: > >>>> On Mon, 19 May 2014 16:23:07 -0700 (PDT) Hugh Dickins wrote: > >>>> > >>>>> Shouldn't FAULT_AROUND_ORDER and fault_around_order be changed to be > >>>>> the order of the fault-around size in bytes, and fault_around_pages() > >>>>> use 1UL << (fault_around_order - PAGE_SHIFT) > >>>> > >>>> Yes. And shame on me for missing it (this time!) at review. > >>>> > >>>> There's still time to fix this. Patches, please. > >>> > >>> Here it is. Made at 3.30 AM, build tested only. > >> > >> Prefer on top of Maddy's patch which makes it always a variable, rather > >> than CONFIG_DEBUG_FS. It's got enough hair as it is. > > > > Something like this? > > > > From: "Kirill A. Shutemov" > > Date: Tue, 20 May 2014 13:02:03 +0300 > > Subject: [PATCH] mm: nominate faultaround area in bytes rather then page order > > > > There are evidences that faultaround feature is less relevant on > > architectures with page size bigger then 4k. Which makes sense since > > page fault overhead per byte of mapped area should be less there. > > > > Let's rework the feature to specify faultaround area in bytes instead of > > page order. It's 64 kilobytes for now. > > > > The patch effectively disables faultaround on architectures with > > page size >= 64k (like ppc64). > > > > It's possible that some other size of faultaround area is relevant for a > > platform. We can expose `fault_around_bytes' variable to arch-specific > > code once such platforms will be found. > > > > Signed-off-by: Kirill A. Shutemov > > --- > > mm/memory.c | 62 +++++++++++++++++++++++-------------------------------------- > > 1 file changed, 23 insertions(+), 39 deletions(-) > > > > diff --git a/mm/memory.c b/mm/memory.c > > index 037b812a9531..252b319e8cdf 100644 > > --- a/mm/memory.c > > +++ b/mm/memory.c > > @@ -3402,63 +3402,47 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address, > > update_mmu_cache(vma, address, pte); > > } > > > > -#define FAULT_AROUND_ORDER 4 > > +static unsigned long fault_around_bytes = 65536; > > + > > +static inline unsigned long fault_around_pages(void) > > +{ > > + return rounddown_pow_of_two(fault_around_bytes) / PAGE_SIZE; > > +} > > + > > +static inline unsigned long fault_around_mask(void) > > +{ > > + return ~(rounddown_pow_of_two(fault_around_bytes) - 1) & PAGE_MASK; > > +} > > > > -#ifdef CONFIG_DEBUG_FS > > -static unsigned int fault_around_order = FAULT_AROUND_ORDER; > > > > -static int fault_around_order_get(void *data, u64 *val) > > +#ifdef CONFIG_DEBUG_FS > > +static int fault_around_bytes_get(void *data, u64 *val) > > { > > - *val = fault_around_order; > > + *val = fault_around_bytes; > > return 0; > > } > > > > -static int fault_around_order_set(void *data, u64 val) > > +static int fault_around_bytes_set(void *data, u64 val) > > { > > Kindly ignore the question if not relevant. Even though we need root > access to alter the value, will we be fine with > negative value?. val is u64. or I miss something? -- Kirill A. Shutemov -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com ([134.134.136.24]:37902 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752015AbaE0KWH (ORCPT ); Tue, 27 May 2014 06:22:07 -0400 From: "Kirill A. Shutemov" In-Reply-To: <53842FB1.7090909@linux.vnet.ibm.com> References: <1399541296-18810-1-git-send-email-maddy@linux.vnet.ibm.com> <537479E7.90806@linux.vnet.ibm.com> <87wqdik4n5.fsf@rustcorp.com.au> <53797511.1050409@linux.vnet.ibm.com> <20140519164301.eafd3dd288ccb88361ddcfc7@linux-foundation.org> <20140520004429.E660AE009B@blue.fi.intel.com> <87oaythsvk.fsf@rustcorp.com.au> <20140520102738.7F096E009B@blue.fi.intel.com> <53842FB1.7090909@linux.vnet.ibm.com> Subject: Re: [PATCH V4 0/2] mm: FAULT_AROUND_ORDER patchset performance data for powerpc Content-Transfer-Encoding: 7bit Message-ID: <20140527102200.012BBE009B@blue.fi.intel.com> Date: Tue, 27 May 2014 13:21:59 +0300 (EEST) Sender: linux-arch-owner@vger.kernel.org List-ID: To: Madhavan Srinivasan Cc: "Kirill A. Shutemov" , Rusty Russell , Andrew Morton , Hugh Dickins , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, x86@kernel.org, benh@kernel.crashing.org, paulus@samba.org, riel@redhat.com, mgorman@suse.de, ak@linux.intel.com, peterz@infradead.org, mingo@kernel.org, dave.hansen@intel.com Message-ID: <20140527102159.HHfsvkr6l90c8n2-fFVaeFww9Xw4hccVSpQ6C8TscaI@z> Madhavan Srinivasan wrote: > On Tuesday 20 May 2014 03:57 PM, Kirill A. Shutemov wrote: > > Rusty Russell wrote: > >> "Kirill A. Shutemov" writes: > >>> Andrew Morton wrote: > >>>> On Mon, 19 May 2014 16:23:07 -0700 (PDT) Hugh Dickins wrote: > >>>> > >>>>> Shouldn't FAULT_AROUND_ORDER and fault_around_order be changed to be > >>>>> the order of the fault-around size in bytes, and fault_around_pages() > >>>>> use 1UL << (fault_around_order - PAGE_SHIFT) > >>>> > >>>> Yes. And shame on me for missing it (this time!) at review. > >>>> > >>>> There's still time to fix this. Patches, please. > >>> > >>> Here it is. Made at 3.30 AM, build tested only. > >> > >> Prefer on top of Maddy's patch which makes it always a variable, rather > >> than CONFIG_DEBUG_FS. It's got enough hair as it is. > > > > Something like this? > > > > From: "Kirill A. Shutemov" > > Date: Tue, 20 May 2014 13:02:03 +0300 > > Subject: [PATCH] mm: nominate faultaround area in bytes rather then page order > > > > There are evidences that faultaround feature is less relevant on > > architectures with page size bigger then 4k. Which makes sense since > > page fault overhead per byte of mapped area should be less there. > > > > Let's rework the feature to specify faultaround area in bytes instead of > > page order. It's 64 kilobytes for now. > > > > The patch effectively disables faultaround on architectures with > > page size >= 64k (like ppc64). > > > > It's possible that some other size of faultaround area is relevant for a > > platform. We can expose `fault_around_bytes' variable to arch-specific > > code once such platforms will be found. > > > > Signed-off-by: Kirill A. Shutemov > > --- > > mm/memory.c | 62 +++++++++++++++++++++++-------------------------------------- > > 1 file changed, 23 insertions(+), 39 deletions(-) > > > > diff --git a/mm/memory.c b/mm/memory.c > > index 037b812a9531..252b319e8cdf 100644 > > --- a/mm/memory.c > > +++ b/mm/memory.c > > @@ -3402,63 +3402,47 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address, > > update_mmu_cache(vma, address, pte); > > } > > > > -#define FAULT_AROUND_ORDER 4 > > +static unsigned long fault_around_bytes = 65536; > > + > > +static inline unsigned long fault_around_pages(void) > > +{ > > + return rounddown_pow_of_two(fault_around_bytes) / PAGE_SIZE; > > +} > > + > > +static inline unsigned long fault_around_mask(void) > > +{ > > + return ~(rounddown_pow_of_two(fault_around_bytes) - 1) & PAGE_MASK; > > +} > > > > -#ifdef CONFIG_DEBUG_FS > > -static unsigned int fault_around_order = FAULT_AROUND_ORDER; > > > > -static int fault_around_order_get(void *data, u64 *val) > > +#ifdef CONFIG_DEBUG_FS > > +static int fault_around_bytes_get(void *data, u64 *val) > > { > > - *val = fault_around_order; > > + *val = fault_around_bytes; > > return 0; > > } > > > > -static int fault_around_order_set(void *data, u64 val) > > +static int fault_around_bytes_set(void *data, u64 val) > > { > > Kindly ignore the question if not relevant. Even though we need root > access to alter the value, will we be fine with > negative value?. val is u64. or I miss something? -- Kirill A. Shutemov