| Date | Tue, 21 Mar 2006 22:31:02 -0800 | From | Chris Wright <> | Subject | [RFC PATCH 22/35] subarch suport for idle loop (NO_IDLE_HZ for Xen) |
| |
Paravirtualize the idle loop to explicitly trap to the hypervisor when blocking, and to use the NO_IDLE_HZ functionality introduced by s390 to inform the rcu subsystem that the CPU is quiescent.
Signed-off-by: Ian Pratt <ian.pratt@xensource.com> Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk> Signed-off-by: Chris Wright <chrisw@sous-sol.org> --- drivers/xen/Kconfig | 8 ++++++++ include/asm-i386/mach-xen/setup_arch_post.h | 24 ++++++++++++++++++++++++ 2 files changed, 32 insertions(+)
--- xen-subarch-2.6.orig/drivers/xen/Kconfig +++ xen-subarch-2.6/drivers/xen/Kconfig @@ -12,6 +12,14 @@ config XEN if XEN +config NO_IDLE_HZ + bool + default y + help + Switches the regular HZ timer off when the system is going idle. + This helps Xen to detect that the Linux system is idle, reducing + the overhead of idle systems. + config XEN_SHADOW_MODE bool default y --- xen-subarch-2.6.orig/include/asm-i386/mach-xen/setup_arch_post.h +++ xen-subarch-2.6/include/asm-i386/mach-xen/setup_arch_post.h @@ -8,6 +8,11 @@ #include <xen/interface/physdev.h> +extern void stop_hz_timer(void); +extern void start_hz_timer(void); + +void xen_idle(void); + static char * __init machine_specific_memory_setup(void) { unsigned long max_pfn = xen_start_info->nr_pages; @@ -74,4 +79,23 @@ static void __init machine_specific_arch console_use_vt = 0; conswitchp = NULL; } + + pm_idle = xen_idle; +} + +void xen_idle(void) +{ + local_irq_disable(); + + if (need_resched()) + local_irq_enable(); + else { + clear_thread_flag(TIF_POLLING_NRFLAG); + smp_mb__after_clear_bit(); + stop_hz_timer(); + /* Blocking includes an implicit local_irq_enable(). */ + HYPERVISOR_sched_op(SCHEDOP_block, 0); + start_hz_timer(); + set_thread_flag(TIF_POLLING_NRFLAG); + } } -- - 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/
|