From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [203.10.76.45]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx.ozlabs.org", Issuer "CA Cert Signing Authority" (verified OK)) by bilbo.ozlabs.org (Postfix) with ESMTPS id D68F8B7094 for ; Tue, 14 Jul 2009 17:00:47 +1000 (EST) Received: from bilbo.ozlabs.org (bilbo.ozlabs.org [203.10.76.25]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "bilbo.ozlabs.org", Issuer "CAcert Class 3 Root" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id B517ADDDE6 for ; Tue, 14 Jul 2009 17:00:47 +1000 (EST) Message-Id: <20090714065425.555222245@samba.org> References: <20090714065350.659537380@samba.org> Date: Tue, 14 Jul 2009 16:53:53 +1000 From: Anton Blanchard To: benh@kernel.crashing.org Subject: [patch 3/3] powerpc: Preload application text segment instead of TASK_UNMAPPED_BASE Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , TASK_UNMAPPED_BASE is not used with the new top down mmap layout. We can reuse this preload slot by loading in the segment at 0x10000000, where almost all PowerPC binaries are linked at. On a microbenchmark that bounces a token between two 64bit processes over pipes and calls gettimeofday each iteration (to access the VDSO), both the 32bit and 64bit context switch rate improves (tested on a 4GHz POWER6): 32bit: 273k/sec -> 283k/sec 64bit: 277k/sec -> 284k/sec Signed-off-by: Anton Blanchard --- Index: linux.trees.git/arch/powerpc/mm/slb.c =================================================================== --- linux.trees.git.orig/arch/powerpc/mm/slb.c 2009-07-14 15:09:39.000000000 +1000 +++ linux.trees.git/arch/powerpc/mm/slb.c 2009-07-14 15:12:42.000000000 +1000 @@ -191,7 +191,7 @@ unsigned long slbie_data = 0; unsigned long pc = KSTK_EIP(tsk); unsigned long stack = KSTK_ESP(tsk); - unsigned long unmapped_base; + unsigned long exec_base; if (!cpu_has_feature(CPU_FTR_NO_SLBIE_B) && offset <= SLB_CACHE_ENTRIES) { @@ -219,14 +219,13 @@ /* * preload some userspace segments into the SLB. + * Almost all 32 and 64bit PowerPC executables are linked at + * 0x10000000 so it makes sense to preload this segment. */ - if (test_tsk_thread_flag(tsk, TIF_32BIT)) - unmapped_base = TASK_UNMAPPED_BASE_USER32; - else - unmapped_base = TASK_UNMAPPED_BASE_USER64; + exec_base = 0x10000000; if (is_kernel_addr(pc) || is_kernel_addr(stack) || - is_kernel_addr(unmapped_base)) + is_kernel_addr(exec_base)) return; slb_allocate(pc); @@ -234,9 +233,9 @@ if (!esids_match(pc, stack)) slb_allocate(stack); - if (!esids_match(pc, unmapped_base) && - !esids_match(stack, unmapped_base)) - slb_allocate(unmapped_base); + if (!esids_match(pc, exec_base) && + !esids_match(stack, exec_base)) + slb_allocate(exec_base); } static inline void patch_slb_encoding(unsigned int *insn_addr, --