Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762435AbYCCXP0 (ORCPT ); Mon, 3 Mar 2008 18:15:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752813AbYCCXPK (ORCPT ); Mon, 3 Mar 2008 18:15:10 -0500 Received: from mga11.intel.com ([192.55.52.93]:18031 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752761AbYCCXPJ (ORCPT ); Mon, 3 Mar 2008 18:15:09 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.25,440,1199692800"; d="scan'208";a="303430431" Message-Id: <20080303230336.042604000@linux-os.sc.intel.com> References: <20080303230335.892214000@linux-os.sc.intel.com> User-Agent: quilt/0.46-1 Date: Mon, 03 Mar 2008 15:02:46 -0800 From: Suresh Siddha To: mingo@elte.hu, hpa@zytor.com, tglx@linutronix.de, andi@firstfloor.org, hch@infradead.org Cc: linux-kernel@vger.kernel.org, Suresh Siddha , Arjan van de Ven Subject: [patch 2/2] x86, fpu: lazy allocation of FPU area - v3 Content-Disposition: inline; filename=x86-lazy-fp-allocation.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5639 Lines: 168 Only allocate the FPU area when the application actually uses FPU, i.e., in the first lazy FPU trap. This could save memory for non-fpu using apps. Signed-off-by: Suresh Siddha Cc: Arjan van de Ven --- v3: Fixed the non-atomic calling sequence in atomic context. v2: Ported to x86.git#testing with some name changes. --- Index: linux-2.6-x86/arch/x86/kernel/i387.c =================================================================== --- linux-2.6-x86.orig/arch/x86/kernel/i387.c 2008-03-03 14:15:17.000000000 -0800 +++ linux-2.6-x86/arch/x86/kernel/i387.c 2008-03-03 14:15:17.000000000 -0800 @@ -9,7 +9,6 @@ #include #include #include -#include #include #include #include @@ -67,7 +66,6 @@ else xstate_size = sizeof(struct i387_fsave_struct); #endif - init_task.thread.xstate = alloc_bootmem(xstate_size); } #ifdef CONFIG_X86_64 @@ -105,6 +103,12 @@ return; } + /* + * Memory allocation at the first usage of the FPU and other state. + */ + if (!tsk->thread.xstate) + tsk->thread.xstate = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL); + if (cpu_has_fxsr) { struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave; Index: linux-2.6-x86/arch/x86/kernel/process.c =================================================================== --- linux-2.6-x86.orig/arch/x86/kernel/process.c 2008-03-03 14:15:17.000000000 -0800 +++ linux-2.6-x86/arch/x86/kernel/process.c 2008-03-03 14:15:17.000000000 -0800 @@ -5,24 +5,33 @@ #include #include -static struct kmem_cache *task_xstate_cachep; +struct kmem_cache *task_xstate_cachep; int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { *dst = *src; - dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL); - if (!dst->thread.xstate) - return -ENOMEM; - WARN_ON((unsigned long)dst->thread.xstate & 15); - memcpy(dst->thread.xstate, src->thread.xstate, xstate_size); + if (src->thread.xstate) { + dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL); + if (!dst->thread.xstate) + return -ENOMEM; + WARN_ON((unsigned long)dst->thread.xstate & 15); + memcpy(dst->thread.xstate, src->thread.xstate, xstate_size); + } return 0; } -void free_thread_info(struct thread_info *ti) +void free_thread_xstate(struct task_struct *tsk) { - kmem_cache_free(task_xstate_cachep, ti->task->thread.xstate); - ti->task->thread.xstate = NULL; + if (tsk->thread.xstate) { + kmem_cache_free(task_xstate_cachep, tsk->thread.xstate); + tsk->thread.xstate = NULL; + } +} + +void free_thread_info(struct thread_info *ti) +{ + free_thread_xstate(ti->task); free_pages((unsigned long)(ti), get_order(THREAD_SIZE)); } Index: linux-2.6-x86/include/asm-x86/processor.h =================================================================== --- linux-2.6-x86.orig/include/asm-x86/processor.h 2008-03-03 14:15:17.000000000 -0800 +++ linux-2.6-x86/include/asm-x86/processor.h 2008-03-03 14:15:17.000000000 -0800 @@ -354,6 +354,8 @@ extern void print_cpu_info(struct cpuinfo_x86 *); extern unsigned int xstate_size; +extern void free_thread_xstate(struct task_struct *); +extern struct kmem_cache *task_xstate_cachep; extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c); extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c); extern unsigned short num_cache_leaves; Index: linux-2.6-x86/arch/x86/kernel/process_32.c =================================================================== --- linux-2.6-x86.orig/arch/x86/kernel/process_32.c 2008-03-03 14:15:17.000000000 -0800 +++ linux-2.6-x86/arch/x86/kernel/process_32.c 2008-03-03 14:15:17.000000000 -0800 @@ -524,6 +524,10 @@ regs->cs = __USER_CS; regs->ip = new_ip; regs->sp = new_sp; + /* + * Free the old FP and other extended state + */ + free_thread_xstate(current); } EXPORT_SYMBOL_GPL(start_thread); Index: linux-2.6-x86/arch/x86/kernel/process_64.c =================================================================== --- linux-2.6-x86.orig/arch/x86/kernel/process_64.c 2008-03-03 14:15:17.000000000 -0800 +++ linux-2.6-x86/arch/x86/kernel/process_64.c 2008-03-03 14:15:17.000000000 -0800 @@ -552,6 +552,10 @@ regs->ss = __USER_DS; regs->flags = 0x200; set_fs(USER_DS); + /* + * Free the old FP and other extended state + */ + free_thread_xstate(current); } EXPORT_SYMBOL_GPL(start_thread); Index: linux-2.6-x86/arch/x86/kernel/traps_32.c =================================================================== --- linux-2.6-x86.orig/arch/x86/kernel/traps_32.c 2008-03-03 14:15:17.000000000 -0800 +++ linux-2.6-x86/arch/x86/kernel/traps_32.c 2008-03-03 14:17:28.000000000 -0800 @@ -1169,9 +1169,20 @@ struct thread_info *thread = current_thread_info(); struct task_struct *tsk = thread->task; - clts(); /* Allow maths ops (or we recurse) */ - if (!tsk_used_math(tsk)) + if (!tsk_used_math(tsk)) { +#ifdef CONFIG_PREEMPT + local_irq_enable(); +#endif + /* + * does a slab alloc which can sleep + */ init_fpu(tsk); +#ifdef CONFIG_PREEMPT + local_irq_disable(); +#endif + } + + clts(); /* Allow maths ops (or we recurse) */ restore_fpu(tsk); thread->status |= TS_USEDFPU; /* So we fnsave on switch_to() */ tsk->fpu_counter++; -- -- 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/