On 11/01/2012 02:47 AM, Marcelo Tosatti wrote:
> Originally from Jeremy Fitzhardinge.
>
> Introduce generic, non hypervisor specific, pvclock initialization
> routines.
>
> Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
>
> Index: vsyscall/arch/x86/kernel/pvclock.c
> ===================================================================
> --- vsyscall.orig/arch/x86/kernel/pvclock.c
> +++ vsyscall/arch/x86/kernel/pvclock.c
> @@ -17,6 +17,10 @@
>
> #include <linux/kernel.h>
> #include <linux/percpu.h>
> +#include <linux/notifier.h>
> +#include <linux/sched.h>
> +#include <linux/gfp.h>
> +#include <linux/bootmem.h>
> #include <asm/pvclock.h>
>
> static u8 valid_flags __read_mostly = 0;
> @@ -122,3 +126,67 @@ void pvclock_read_wallclock(struct pvclo
>
> set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
> }
> +
> +static aligned_pvti_t *pvclock_vdso_info;
is there a non-aligned pvti ?
I would also add that "pvti" is not exactly the most descriptive name
I've seen.
> +
> +static struct pvclock_vsyscall_time_info *
> +pvclock_get_vsyscall_user_time_info(int cpu)
> +{
> + if (pvclock_vdso_info == NULL) {
> + BUG();
> + return NULL;
> + }
> +
> + return &pvclock_vdso_info[cpu].info;
> +}
> +
if (!pvclock_vdso_info)
BUG();
return &pvclock...
> +struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu)
> +{
> + return &pvclock_get_vsyscall_user_time_info(cpu)->pvti;
> +}
> +
> +int pvclock_task_migrate(struct notifier_block *nb, unsigned long l, void *v)
> +{
> + struct task_migration_notifier *mn = v;
> + struct pvclock_vsyscall_time_info *pvti;
> +
> + pvti = pvclock_get_vsyscall_user_time_info(mn->from_cpu);
> +
> + if (pvti == NULL)
> + return NOTIFY_DONE;
> +
When is it NULL? IIUC, this is when the vsyscall is disabled, right?
Would you mind adding comments for it?
Also, this is supposed to be an unlikely branch, right?
> + pvti->migrate_count++;
> +
> + return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block pvclock_migrate = {
> + .notifier_call = pvclock_task_migrate,
> +};
> +
> +/*
> + * Initialize the generic pvclock vsyscall state. This will allocate
> + * a/some page(s) for the per-vcpu pvclock information, set up a
> + * fixmap mapping for the page(s)
> + */
> +int __init pvclock_init_vsyscall(void)
> +{
> + int idx;
> + unsigned int size = PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE;
> +
> + pvclock_vdso_info = __alloc_bootmem(size, PAGE_SIZE, 0);
This will be the most critical path for reading pvclock's time data. So
why can't we:
1) Make it per-node.
2) Of course, as a consequence, make sure all info structures in the
same page are in the same node ?
> + if (!pvclock_vdso_info)
> + return -ENOMEM;
> +
> + memset(pvclock_vdso_info, 0, size);
> +
> + for (idx = 0; idx <= (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) {
> + __set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx,
> + __pa_symbol(pvclock_vdso_info) + (idx*PAGE_SIZE),
> + PAGE_KERNEL_VVAR);
> + }
> +
> + register_task_migration_notifier(&pvclock_migrate);
> +
> + return 0;
> +}
> Index: vsyscall/arch/x86/include/asm/fixmap.h
> ===================================================================
> --- vsyscall.orig/arch/x86/include/asm/fixmap.h
> +++ vsyscall/arch/x86/include/asm/fixmap.h
> @@ -19,6 +19,7 @@
> #include <asm/acpi.h>
> #include <asm/apicdef.h>
> #include <asm/page.h>
> +#include <asm/pvclock.h>
> #ifdef CONFIG_X86_32
> #include <linux/threads.h>
> #include <asm/kmap_types.h>
> @@ -81,6 +82,10 @@ enum fixed_addresses {
> VVAR_PAGE,
> VSYSCALL_HPET,
> #endif
> +#ifdef CONFIG_PARAVIRT_CLOCK
> + PVCLOCK_FIXMAP_BEGIN,
> + PVCLOCK_FIXMAP_END = PVCLOCK_FIXMAP_BEGIN+PVCLOCK_VSYSCALL_NR_PAGES-1,
> +#endif
> FIX_DBGP_BASE,
> FIX_EARLYCON_MEM_BASE,
> #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
> Index: vsyscall/arch/x86/include/asm/pvclock.h
> ===================================================================
> --- vsyscall.orig/arch/x86/include/asm/pvclock.h
> +++ vsyscall/arch/x86/include/asm/pvclock.h
> @@ -13,6 +13,8 @@ void pvclock_read_wallclock(struct pvclo
> struct pvclock_vcpu_time_info *vcpu,
> struct timespec *ts);
> void pvclock_resume(void);
> +int __init pvclock_init_vsyscall(void);
> +struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu);
>
> /*
> * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
> @@ -85,4 +87,17 @@ unsigned __pvclock_read_cycles(const str
> return version;
> }
>
> +struct pvclock_vsyscall_time_info {
> + struct pvclock_vcpu_time_info pvti;
> + u32 migrate_count;
> +};
> +
> +typedef union {
> + struct pvclock_vsyscall_time_info info;
> + char pad[SMP_CACHE_BYTES];
> +} aligned_pvti_t ____cacheline_aligned;
Please, just align pvclock_vsyscall_time_info. It is 10 thousand times
more descriptive.
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