From efcac6589a277c10060e4be44b9455cf43838dc1 Mon Sep 17 00:00:00 2001 From: Alexey Kardashevskiy Date: Wed, 2 Mar 2011 15:18:48 +0000 Subject: powerpc: Per process DSCR + some fixes (try#4) The DSCR (aka Data Stream Control Register) is supported on some server PowerPC chips and allow some control over the prefetch of data streams. This patch allows the value to be specified per thread by emulating the corresponding mfspr and mtspr instructions. Children of such threads inherit the value. Other threads use a default value that can be specified in sysfs - /sys/devices/system/cpu/dscr_default. If a thread starts with non default value in the sysfs entry, all children threads inherit this non default value even if the sysfs value is changed later. Signed-off-by: Alexey Kardashevskiy Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/process.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/powerpc/kernel/process.c') diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index f74f355a9617..a01c2d93fd2f 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -702,6 +702,8 @@ void prepare_to_copy(struct task_struct *tsk) /* * Copy a thread.. */ +extern unsigned long dscr_default; /* defined in arch/powerpc/kernel/sysfs.c */ + int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long unused, struct task_struct *p, struct pt_regs *regs) @@ -769,6 +771,20 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, p->thread.ksp_vsid = sp_vsid; } #endif /* CONFIG_PPC_STD_MMU_64 */ +#ifdef CONFIG_PPC64 + if (cpu_has_feature(CPU_FTR_DSCR)) { + if (current->thread.dscr_inherit) { + p->thread.dscr_inherit = 1; + p->thread.dscr = current->thread.dscr; + } else if (0 != dscr_default) { + p->thread.dscr_inherit = 1; + p->thread.dscr = dscr_default; + } else { + p->thread.dscr_inherit = 0; + p->thread.dscr = 0; + } + } +#endif /* * The PPC64 ABI makes use of a TOC to contain function -- cgit v1.2.3