search for: timer_irq_works

The timer_irq_works() boot check may sometimes fail in a VM, when the Host is overcommitted or when the Guest is running nested. Since the intended check is unnecessary on VMware's virtual hardware, this change by-passes it. Signed-off-by: Renat Valiullin <rvaliullin at vmware.com> Acked-by: Alok N Kataria...

The timer_irq_works() boot check may sometimes fail in a VM, when the Host is overcommitted or when the Guest is running nested. Since the intended check is unnecessary on VMware's virtual hardware, this change by-passes it. Signed-off-by: Renat Valiullin <rvaliullin at vmware.com> Acked-by: Alok N Kataria...

....h> #include <mach_apic.h> +#include <mach_apictimer.h> #include "io_ports.h" @@ -1864,7 +1865,7 @@ static void __init setup_ioapic_ids_from * - if this function detects that timer IRQs are defunct, then we fall * back to ISA timer IRQs */ -static int __init timer_irq_works(void) +int __init timer_irq_works(void) { unsigned long t1 = jiffies; @@ -2285,7 +2286,7 @@ static inline void check_timer(void) * Ok, does IRQ0 through the IOAPIC work? */ unmask_IO_APIC_irq(0); - if (timer_irq_works()) { + if (mach_timer_irq_works()) { if (nmi_watchdog == NM...

....h> #include <mach_apic.h> +#include <mach_apictimer.h> #include "io_ports.h" @@ -1864,7 +1865,7 @@ static void __init setup_ioapic_ids_from * - if this function detects that timer IRQs are defunct, then we fall * back to ISA timer IRQs */ -static int __init timer_irq_works(void) +int __init timer_irq_works(void) { unsigned long t1 = jiffies; @@ -2285,7 +2286,7 @@ static inline void check_timer(void) * Ok, does IRQ0 through the IOAPIC work? */ unmask_IO_APIC_irq(0); - if (timer_irq_works()) { + if (mach_timer_irq_works()) { if (nmi_watchdog == NM...

And I think current issue with "Kernel panic - not syncing: IO-APIC + timer doesn't work!" is also clear. timer_irq_works(void) never returns 1: https://github.com/torvalds/linux/blob/d966564fcdc19e13eb6ba1fbe6b8101070339c3d/arch/x86/kernel/apic/io_apic.c#L1641 I think it happens because of jiffies (http://www.makelinux.net/books/lkd2/ch10lev1sec3#ch10fig01) It should have the same address as jiffies_64: https://git...

...der SMP boards, their mptable lies * about the timer IRQ. We do the following to work around the situation: @@ -1872,9 +1881,12 @@ static void __init setup_ioapic_ids_from * - if this function detects that timer IRQs are defunct, then we fall * back to ISA timer IRQs */ -static int __init timer_irq_works(void) +int __init timer_irq_works(void) { unsigned long t1 = jiffies; + + if (timer_irq_really_works) + return 1; local_irq_enable(); /* Let ten ticks pass... */ @@ -2146,7 +2158,7 @@ int timer_uses_ioapic_pin_0; * is so screwy. Thanks to Brian Perkins for testing/hacking this beast...

...der SMP boards, their mptable lies * about the timer IRQ. We do the following to work around the situation: @@ -1872,9 +1881,12 @@ static void __init setup_ioapic_ids_from * - if this function detects that timer IRQs are defunct, then we fall * back to ISA timer IRQs */ -static int __init timer_irq_works(void) +int __init timer_irq_works(void) { unsigned long t1 = jiffies; + + if (timer_irq_really_works) + return 1; local_irq_enable(); /* Let ten ticks pass... */ @@ -2146,7 +2158,7 @@ int timer_uses_ioapic_pin_0; * is so screwy. Thanks to Brian Perkins for testing/hacking this beast...

...nasty bug in some older SMP boards, their mptable lies - * about the timer IRQ. We do the following to work around the situation: - * - * - timer IRQ defaults to IO-APIC IRQ - * - if this function detects that timer IRQs are defunct, then we fall - * back to ISA timer IRQs - */ -static int __init timer_irq_works(void) -{ - unsigned long t1 = jiffies; - - local_irq_enable(); - /* Let ten ticks pass... */ - mdelay((10 * 1000) / HZ); - - /* - * Expect a few ticks at least, to be sure some possible - * glue logic does not lock up after one or two first - * ticks in a non-ExtINT mode. Also the local APIC -...

...nasty bug in some older SMP boards, their mptable lies - * about the timer IRQ. We do the following to work around the situation: - * - * - timer IRQ defaults to IO-APIC IRQ - * - if this function detects that timer IRQs are defunct, then we fall - * back to ISA timer IRQs - */ -static int __init timer_irq_works(void) -{ - unsigned long t1 = jiffies; - - local_irq_enable(); - /* Let ten ticks pass... */ - mdelay((10 * 1000) / HZ); - - /* - * Expect a few ticks at least, to be sure some possible - * glue logic does not lock up after one or two first - * ticks in a non-ExtINT mode. Also the local APIC -...

...ors? How do I get rid of it? > > Regards, > Dmitry > > > 20.02.2017, 17:51, "George Rimar" <grimar at accesssoftek.com>: > > And I think current issue with "Kernel panic - not syncing: IO-APIC + > timer doesn't work!" is also clear. > > timer_irq_works(void) never returns 1: > https://github.com/torvalds/linux/blob/d966564fcdc19e13eb6ba1fbe6b810 > 1070339c3d/arch/x86/kernel/apic/io_apic.c#L1641 > > I think it happens because of jiffies (http://www.makelinux.net/ > books/lkd2/ch10lev1sec3#ch10fig01) > > It should have the same...

Thanks for your ideas, Sean ! >The bug is not likely to be corrupted data in the decompressed output (that is just calling into a gzip routine or something). You shouldn't have to dump/printf->trace from memory during boot to see that data since the "real" kernel binary that is being decompressed into that memory region is probably already somewhere > in your build tree

...interrupt. This method for determining a cycle counter frequency is unreliable on virtual hardware since the VCPU may be preempted by the hypervisor during this calculation. Instead, the VMI Time device determines the frequency of the VMI cycle counters by querying the VMI. 2) The timer_irq_works() algorithm is problematic in a virtual environment for various reasons, and is avoided. When running on a hypervisor, the kernel can assume that the alarm will be wired up correctly to the interrupt controller and this logic is avoided altogether. 3) Rather than keeping kernel time stat...

...interrupt. This method for determining a cycle counter frequency is unreliable on virtual hardware since the VCPU may be preempted by the hypervisor during this calculation. Instead, the VMI Time device determines the frequency of the VMI cycle counters by querying the VMI. 2) The timer_irq_works() algorithm is problematic in a virtual environment for various reasons, and is avoided. When running on a hypervisor, the kernel can assume that the alarm will be wired up correctly to the interrupt controller and this logic is avoided altogether. 3) Rather than keeping kernel time stat...

Setting the IF flag can cause an VM exit. So we should avoid touching the IF flag until absolutely necessary. This patch change the way the paravirt arch_local_irq_restore() works by checking the previous flags value and call arch_local_irq_enable() only if the IF flag was set previously. On a 32 vCPUs KVM guest running the AIM7 five-sec workload, the performance increased slightly from 302136.32

Setting the IF flag can cause an VM exit. So we should avoid touching the IF flag until absolutely necessary. This patch change the way the paravirt arch_local_irq_restore() works by checking the previous flags value and call arch_local_irq_enable() only if the IF flag was set previously. On a 32 vCPUs KVM guest running the AIM7 five-sec workload, the performance increased slightly from 302136.32