From: Christoph Lameter <cl@linux.com> To: Tejun Heo <tj@kernel.org> Cc: akpm@linuxfoundation.org, Steven Rostedt <rostedt@goodmis.org>, Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@redhat.com> Cc: linux-arch@vger.kernel.org Cc: Steven Rostedt <srostedt@redhat.com> Cc: linux-kernel@vger.kernel.org Subject: [guv v2 08/31] tracing: Replace __get_cpu_var uses Date: Mon, 26 Aug 2013 20:44:37 +0000 [thread overview] Message-ID: <00000140bc5f00c2-8e9ffffa-de46-4329-aef3-317c258828bd-000000@email.amazonses.com> (raw) In-Reply-To: 20130826204351.725357339@linux.com __get_cpu_var() is used for multiple purposes in the kernel source. One of them is address calculation via the form &__get_cpu_var(x). This calculates the address for the instance of the percpu variable of the current processor based on an offset. Others usage cases are for storing and retrieving data from the current processors percpu area. __get_cpu_var() can be used as an lvalue when writing data or on the right side of an assignment. __get_cpu_var() is defined as : #define __get_cpu_var(var) (*this_cpu_ptr(&(var))) __get_cpu_var() always only does a address determination. However, store and retrieve operations could use a segment prefix (or global register on other platforms) to avoid the address calculation. this_cpu_write() and this_cpu_read() can directly take an offset into a percpu area and use optimized assembly code to read and write per cpu variables. This patch converts __get_cpu_var into either and explicit address calculation using this_cpu_ptr() or into a use of this_cpu operations that use the offset. Thereby address calcualtions are avoided and less registers are used when code is generated. At the end of the patchset all uses of __get_cpu_var have been removed so the macro is removed too. The patchset includes passes over all arches as well. Once these operations are used throughout then specialized macros can be defined in non -x86 arches as well in order to optimize per cpu access by f.e. using a global register that may be set to the per cpu base. Transformations done to __get_cpu_var() 1. Determine the address of the percpu instance of the current processor. DEFINE_PER_CPU(int, y); int *x = &__get_cpu_var(y); Converts to int *x = this_cpu_ptr(&y); 2. Same as #1 but this time an array structure is involved. DEFINE_PER_CPU(int, y[20]); int *x = __get_cpu_var(y); Converts to int *x = this_cpu_ptr(y); 3. Retrieve the content of the current processors instance of a per cpu variable. DEFINE_PER_CPU(int, u); int x = __get_cpu_var(y) Converts to int x = __this_cpu_read(y); 4. Retrieve the content of a percpu struct DEFINE_PER_CPU(struct mystruct, y); struct mystruct x = __get_cpu_var(y); Converts to memcpy(this_cpu_ptr(&y), x, sizeof(x)); 5. Assignment to a per cpu variable DEFINE_PER_CPU(int, y) __get_cpu_var(y) = x; Converts to this_cpu_write(y, x); 6. Increment/Decrement etc of a per cpu variable DEFINE_PER_CPU(int, y); __get_cpu_var(y)++ Converts to this_cpu_inc(y) Signed-off-by: Christoph Lameter <cl@linux.com> Index: linux/include/linux/kprobes.h =================================================================== --- linux.orig/include/linux/kprobes.h 2013-08-26 14:25:53.000000000 -0500 +++ linux/include/linux/kprobes.h 2013-08-26 14:26:29.460993659 -0500 @@ -329,7 +329,7 @@ static inline void reset_current_kprobe( static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) { - return (&__get_cpu_var(kprobe_ctlblk)); + return this_cpu_ptr(&kprobe_ctlblk); } int register_kprobe(struct kprobe *p); Index: linux/kernel/trace/ftrace.c =================================================================== --- linux.orig/kernel/trace/ftrace.c 2013-08-26 14:25:53.000000000 -0500 +++ linux/kernel/trace/ftrace.c 2013-08-26 14:26:29.460993659 -0500 @@ -870,7 +870,7 @@ function_profile_call(unsigned long ip, local_irq_save(flags); - stat = &__get_cpu_var(ftrace_profile_stats); + stat = this_cpu_ptr(&ftrace_profile_stats); if (!stat->hash || !ftrace_profile_enabled) goto out; @@ -901,7 +901,7 @@ static void profile_graph_return(struct unsigned long flags; local_irq_save(flags); - stat = &__get_cpu_var(ftrace_profile_stats); + stat = this_cpu_ptr(&ftrace_profile_stats); if (!stat->hash || !ftrace_profile_enabled) goto out; Index: linux/kernel/trace/trace.c =================================================================== --- linux.orig/kernel/trace/trace.c 2013-08-26 14:25:53.000000000 -0500 +++ linux/kernel/trace/trace.c 2013-08-26 14:26:29.464993617 -0500 @@ -1676,7 +1676,7 @@ static void __ftrace_trace_stack(struct */ barrier(); if (use_stack == 1) { - trace.entries = &__get_cpu_var(ftrace_stack).calls[0]; + trace.entries = this_cpu_ptr(ftrace_stack.calls); trace.max_entries = FTRACE_STACK_MAX_ENTRIES; if (regs)
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Lameter <cl@linux.com> To: Tejun Heo <tj@kernel.org> Cc: akpm@linuxfoundation.org, Steven Rostedt <rostedt@goodmis.org>, Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@redhat.com>, linux-arch@vger.kernel.org, Steven Rostedt <srostedt@redhat.com>, linux-kernel@vger.kernel.org Subject: [guv v2 08/31] tracing: Replace __get_cpu_var uses Date: Mon, 26 Aug 2013 20:44:37 +0000 [thread overview] Message-ID: <00000140bc5f00c2-8e9ffffa-de46-4329-aef3-317c258828bd-000000@email.amazonses.com> (raw) In-Reply-To: 20130826204351.725357339@linux.com __get_cpu_var() is used for multiple purposes in the kernel source. One of them is address calculation via the form &__get_cpu_var(x). This calculates the address for the instance of the percpu variable of the current processor based on an offset. Others usage cases are for storing and retrieving data from the current processors percpu area. __get_cpu_var() can be used as an lvalue when writing data or on the right side of an assignment. __get_cpu_var() is defined as : #define __get_cpu_var(var) (*this_cpu_ptr(&(var))) __get_cpu_var() always only does a address determination. However, store and retrieve operations could use a segment prefix (or global register on other platforms) to avoid the address calculation. this_cpu_write() and this_cpu_read() can directly take an offset into a percpu area and use optimized assembly code to read and write per cpu variables. This patch converts __get_cpu_var into either and explicit address calculation using this_cpu_ptr() or into a use of this_cpu operations that use the offset. Thereby address calcualtions are avoided and less registers are used when code is generated. At the end of the patchset all uses of __get_cpu_var have been removed so the macro is removed too. The patchset includes passes over all arches as well. Once these operations are used throughout then specialized macros can be defined in non -x86 arches as well in order to optimize per cpu access by f.e. using a global register that may be set to the per cpu base. Transformations done to __get_cpu_var() 1. Determine the address of the percpu instance of the current processor. DEFINE_PER_CPU(int, y); int *x = &__get_cpu_var(y); Converts to int *x = this_cpu_ptr(&y); 2. Same as #1 but this time an array structure is involved. DEFINE_PER_CPU(int, y[20]); int *x = __get_cpu_var(y); Converts to int *x = this_cpu_ptr(y); 3. Retrieve the content of the current processors instance of a per cpu variable. DEFINE_PER_CPU(int, u); int x = __get_cpu_var(y) Converts to int x = __this_cpu_read(y); 4. Retrieve the content of a percpu struct DEFINE_PER_CPU(struct mystruct, y); struct mystruct x = __get_cpu_var(y); Converts to memcpy(this_cpu_ptr(&y), x, sizeof(x)); 5. Assignment to a per cpu variable DEFINE_PER_CPU(int, y) __get_cpu_var(y) = x; Converts to this_cpu_write(y, x); 6. Increment/Decrement etc of a per cpu variable DEFINE_PER_CPU(int, y); __get_cpu_var(y)++ Converts to this_cpu_inc(y) Signed-off-by: Christoph Lameter <cl@linux.com> Index: linux/include/linux/kprobes.h =================================================================== --- linux.orig/include/linux/kprobes.h 2013-08-26 14:25:53.000000000 -0500 +++ linux/include/linux/kprobes.h 2013-08-26 14:26:29.460993659 -0500 @@ -329,7 +329,7 @@ static inline void reset_current_kprobe( static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void) { - return (&__get_cpu_var(kprobe_ctlblk)); + return this_cpu_ptr(&kprobe_ctlblk); } int register_kprobe(struct kprobe *p); Index: linux/kernel/trace/ftrace.c =================================================================== --- linux.orig/kernel/trace/ftrace.c 2013-08-26 14:25:53.000000000 -0500 +++ linux/kernel/trace/ftrace.c 2013-08-26 14:26:29.460993659 -0500 @@ -870,7 +870,7 @@ function_profile_call(unsigned long ip, local_irq_save(flags); - stat = &__get_cpu_var(ftrace_profile_stats); + stat = this_cpu_ptr(&ftrace_profile_stats); if (!stat->hash || !ftrace_profile_enabled) goto out; @@ -901,7 +901,7 @@ static void profile_graph_return(struct unsigned long flags; local_irq_save(flags); - stat = &__get_cpu_var(ftrace_profile_stats); + stat = this_cpu_ptr(&ftrace_profile_stats); if (!stat->hash || !ftrace_profile_enabled) goto out; Index: linux/kernel/trace/trace.c =================================================================== --- linux.orig/kernel/trace/trace.c 2013-08-26 14:25:53.000000000 -0500 +++ linux/kernel/trace/trace.c 2013-08-26 14:26:29.464993617 -0500 @@ -1676,7 +1676,7 @@ static void __ftrace_trace_stack(struct */ barrier(); if (use_stack == 1) { - trace.entries = &__get_cpu_var(ftrace_stack).calls[0]; + trace.entries = this_cpu_ptr(ftrace_stack.calls); trace.max_entries = FTRACE_STACK_MAX_ENTRIES; if (regs)
next prev parent reply other threads:[~2013-08-26 20:51 UTC|newest] Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <20130826204351.725357339@linux.com> 2013-08-26 20:44 ` [guv v2 02/31] percpu: Make __verify_pcu_ptr handle per cpu pointers to arrays Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 03/31] Coccinelle script for __get_cpu_var conversion Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 05/31] time: Replace __get_cpu_var uses Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 04/31] net: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 06/31] scheduler: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter [this message] 2013-08-26 20:44 ` [guv v2 08/31] tracing: " Christoph Lameter 2013-08-28 19:48 ` Steven Rostedt 2013-08-29 3:44 ` Masami Hiramatsu 2013-08-29 16:35 ` Christoph Lameter 2013-08-30 7:00 ` Ingo Molnar 2013-08-26 20:44 ` [guv v2 09/31] block: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 11/31] percpu: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 07/31] mm: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 10/31] rcu: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 14/31] drivers: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 13/31] kernel misc: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 12/31] watchdog: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 18/31] s390: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-28 6:27 ` Heiko Carstens 2013-08-26 20:44 ` [guv v2 17/31] mips: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 15/31] zcache/zsmalloc: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 16/31] x86: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 01/31] x86: Use this_cpu_inc/dec for debug registers Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 19/31] ia64: Replace __get_cpu_var uses Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 20/31] powerpc: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-27 8:44 ` Geert Uytterhoeven 2013-08-27 15:37 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 21/31] sparc: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-26 20:44 ` [guv v2 22/31] arm: " Christoph Lameter 2013-08-26 20:44 ` Christoph Lameter 2013-08-27 9:41 ` Catalin Marinas 2013-08-26 20:56 ` [guv v2 25/31] avr32: " Christoph Lameter 2013-08-26 20:56 ` Christoph Lameter 2013-08-27 6:58 ` Hans-Christian Egtvedt 2013-08-26 20:56 ` [guv v2 23/31] tile: " Christoph Lameter 2013-08-26 20:56 ` Christoph Lameter 2013-08-26 22:22 ` Chris Metcalf 2013-08-26 22:22 ` Chris Metcalf 2013-08-27 14:48 ` Christoph Lameter 2013-08-28 17:19 ` Chris Metcalf 2013-08-28 17:19 ` Chris Metcalf 2013-08-28 17:54 ` Christoph Lameter 2013-08-28 18:13 ` Chris Metcalf 2013-08-28 18:13 ` Chris Metcalf 2013-08-28 18:22 ` Christoph Lameter 2013-08-30 16:01 ` Chris Metcalf 2013-08-30 16:01 ` Chris Metcalf 2013-08-26 20:56 ` [guv v2 29/31] parisc: " Christoph Lameter 2013-08-26 20:56 ` Christoph Lameter 2013-08-26 20:56 ` Christoph Lameter 2013-08-26 21:16 ` [guv v2 31/31] Remove __get_cpu_var and __raw_get_cpu_var macros Christoph Lameter 2013-08-26 21:16 ` Christoph Lameter 2013-08-26 21:16 ` [guv v2 24/31] blackfin: Replace __get_cpu_var uses Christoph Lameter 2013-08-26 21:16 ` Christoph Lameter 2013-08-26 21:16 ` [guv v2 26/31] alpha: Replace __get_cpu_var Christoph Lameter 2013-08-26 21:16 ` Christoph Lameter 2013-08-26 21:56 ` [guv v2 30/31] metag: Replace __get_cpu_var uses Christoph Lameter 2013-08-26 21:56 ` Christoph Lameter 2013-08-27 9:53 ` James Hogan 2013-08-27 9:53 ` James Hogan 2013-08-26 21:56 ` [guv v2 28/31] arc: Replace __get_cpu_var uses throughout the kernel Christoph Lameter 2013-08-26 21:56 ` Christoph Lameter [not found] ` <521C2A9F.3070400@synopsys.com> [not found] ` <00000140c05d28b7-f0a2bc86-fe85-40f7-b627-32664cd616a4-000000@email.amazonses.com> 2013-08-28 4:24 ` Vineet Gupta 2013-08-28 13:46 ` Christoph Lameter 2013-08-26 21:56 ` [guv v2 27/31] sh: " Christoph Lameter 2013-08-26 21:56 ` Christoph Lameter 2013-08-26 21:56 ` Christoph Lameter 2013-09-02 21:35 ` [guv v2 04/31] net: Replace __get_cpu_var uses David Howells 2013-09-03 3:33 ` David Miller 2013-09-03 14:21 ` Christoph Lameter 2013-09-03 14:20 ` Christoph Lameter 2013-09-03 20:39 ` David Howells
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