Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754008Ab2KQAvS (ORCPT ); Fri, 16 Nov 2012 19:51:18 -0500 Received: from terminus.zytor.com ([198.137.202.10]:37876 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753825Ab2KQAvQ (ORCPT ); Fri, 16 Nov 2012 19:51:16 -0500 Date: Fri, 16 Nov 2012 16:50:39 -0800 From: tip-bot for Alexander Duyck Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, alexander.h.duyck@intel.com, tglx@linutronix.de, hpa@linux.intel.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, alexander.h.duyck@intel.com, tglx@linutronix.de, hpa@linux.intel.com In-Reply-To: <20121116215315.8521.46270.stgit@ahduyck-cp1.jf.intel.com> References: <20121116215315.8521.46270.stgit@ahduyck-cp1.jf.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86: Improve __phys_addr performance by making use of carry flags and inlining Git-Commit-ID: 0bdf525f04afd3a32c14e5a8778771f9c9e0f074 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Fri, 16 Nov 2012 16:51:08 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4991 Lines: 147 Commit-ID: 0bdf525f04afd3a32c14e5a8778771f9c9e0f074 Gitweb: http://git.kernel.org/tip/0bdf525f04afd3a32c14e5a8778771f9c9e0f074 Author: Alexander Duyck AuthorDate: Fri, 16 Nov 2012 13:53:51 -0800 Committer: H. Peter Anvin CommitDate: Fri, 16 Nov 2012 16:42:08 -0800 x86: Improve __phys_addr performance by making use of carry flags and inlining This patch is meant to improve overall system performance when making use of the __phys_addr call. To do this I have implemented several changes. First if CONFIG_DEBUG_VIRTUAL is not defined __phys_addr is made an inline, similar to how this is currently handled in 32 bit. However in order to do this it is required to export phys_base so that it is available if __phys_addr is used in kernel modules. The second change was to streamline the code by making use of the carry flag on an add operation instead of performing a compare on a 64 bit value. The advantage to this is that it allows us to significantly reduce the overall size of the call. On my Xeon E5 system the entire __phys_addr inline call consumes a little less than 32 bytes and 5 instructions. I also applied similar logic to the debug version of the function. My testing shows that the debug version of the function with this patch applied is slightly faster than the non-debug version without the patch. Finally I also applied the same logic changes to __virt_addr_valid since it used the same general code flow as __phys_addr and could achieve similar gains though these changes. Signed-off-by: Alexander Duyck Link: http://lkml.kernel.org/r/20121116215315.8521.46270.stgit@ahduyck-cp1.jf.intel.com Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/page_64.h | 14 ++++++++++++++ arch/x86/kernel/x8664_ksyms_64.c | 3 +++ arch/x86/mm/physaddr.c | 40 +++++++++++++++++++++++++--------------- 3 files changed, 42 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h index 4150999..5138174 100644 --- a/arch/x86/include/asm/page_64.h +++ b/arch/x86/include/asm/page_64.h @@ -9,7 +9,21 @@ extern unsigned long max_pfn; extern unsigned long phys_base; +static inline unsigned long __phys_addr_nodebug(unsigned long x) +{ + unsigned long y = x - __START_KERNEL_map; + + /* use the carry flag to determine if x was < __START_KERNEL_map */ + x = y + ((x > y) ? phys_base : (__START_KERNEL_map - PAGE_OFFSET)); + + return x; +} + +#ifdef CONFIG_DEBUG_VIRTUAL extern unsigned long __phys_addr(unsigned long); +#else +#define __phys_addr(x) __phys_addr_nodebug(x) +#endif #define __phys_reloc_hide(x) (x) diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c index 1330dd1..b014d94 100644 --- a/arch/x86/kernel/x8664_ksyms_64.c +++ b/arch/x86/kernel/x8664_ksyms_64.c @@ -59,6 +59,9 @@ EXPORT_SYMBOL(memcpy); EXPORT_SYMBOL(__memcpy); EXPORT_SYMBOL(memmove); +#ifndef CONFIG_DEBUG_VIRTUAL +EXPORT_SYMBOL(phys_base); +#endif EXPORT_SYMBOL(empty_zero_page); #ifndef CONFIG_PARAVIRT EXPORT_SYMBOL(native_load_gs_index); diff --git a/arch/x86/mm/physaddr.c b/arch/x86/mm/physaddr.c index d2e2735..fd40d75 100644 --- a/arch/x86/mm/physaddr.c +++ b/arch/x86/mm/physaddr.c @@ -8,33 +8,43 @@ #ifdef CONFIG_X86_64 +#ifdef CONFIG_DEBUG_VIRTUAL unsigned long __phys_addr(unsigned long x) { - if (x >= __START_KERNEL_map) { - x -= __START_KERNEL_map; - VIRTUAL_BUG_ON(x >= KERNEL_IMAGE_SIZE); - x += phys_base; + unsigned long y = x - __START_KERNEL_map; + + /* use the carry flag to determine if x was < __START_KERNEL_map */ + if (unlikely(x > y)) { + x = y + phys_base; + + VIRTUAL_BUG_ON(y >= KERNEL_IMAGE_SIZE); } else { - VIRTUAL_BUG_ON(x < PAGE_OFFSET); - x -= PAGE_OFFSET; - VIRTUAL_BUG_ON(!phys_addr_valid(x)); + x = y + (__START_KERNEL_map - PAGE_OFFSET); + + /* carry flag will be set if starting x was >= PAGE_OFFSET */ + VIRTUAL_BUG_ON((x > y) || !phys_addr_valid(x)); } + return x; } EXPORT_SYMBOL(__phys_addr); +#endif bool __virt_addr_valid(unsigned long x) { - if (x >= __START_KERNEL_map) { - x -= __START_KERNEL_map; - if (x >= KERNEL_IMAGE_SIZE) + unsigned long y = x - __START_KERNEL_map; + + /* use the carry flag to determine if x was < __START_KERNEL_map */ + if (unlikely(x > y)) { + x = y + phys_base; + + if (y >= KERNEL_IMAGE_SIZE) return false; - x += phys_base; } else { - if (x < PAGE_OFFSET) - return false; - x -= PAGE_OFFSET; - if (!phys_addr_valid(x)) + x = y + (__START_KERNEL_map - PAGE_OFFSET); + + /* carry flag will be set if starting x was >= PAGE_OFFSET */ + if ((x > y) || !phys_addr_valid(x)) return false; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/