diff options
| -rw-r--r-- | Documentation/x86/intel_rdt_ui.txt | 114 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/apic.c | 8 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/vector.c | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/mcheck/mce_amd.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/mcheck/therm_throt.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/mcheck/threshold.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/irq.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/irq_work.c | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/setup.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/smp.c | 15 |
10 files changed, 144 insertions, 22 deletions
diff --git a/Documentation/x86/intel_rdt_ui.txt b/Documentation/x86/intel_rdt_ui.txt index d918d268cd72..51cf6fa5591f 100644 --- a/Documentation/x86/intel_rdt_ui.txt +++ b/Documentation/x86/intel_rdt_ui.txt @@ -212,3 +212,117 @@ Finally we move core 4-7 over to the new group and make sure that the kernel and the tasks running there get 50% of the cache. # echo C0 > p0/cpus + +4) Locking between applications + +Certain operations on the resctrl filesystem, composed of read/writes +to/from multiple files, must be atomic. + +As an example, the allocation of an exclusive reservation of L3 cache +involves: + + 1. Read the cbmmasks from each directory + 2. Find a contiguous set of bits in the global CBM bitmask that is clear + in any of the directory cbmmasks + 3. Create a new directory + 4. Set the bits found in step 2 to the new directory "schemata" file + +If two applications attempt to allocate space concurrently then they can +end up allocating the same bits so the reservations are shared instead of +exclusive. + +To coordinate atomic operations on the resctrlfs and to avoid the problem +above, the following locking procedure is recommended: + +Locking is based on flock, which is available in libc and also as a shell +script command + +Write lock: + + A) Take flock(LOCK_EX) on /sys/fs/resctrl + B) Read/write the directory structure. + C) funlock + +Read lock: + + A) Take flock(LOCK_SH) on /sys/fs/resctrl + B) If success read the directory structure. + C) funlock + +Example with bash: + +# Atomically read directory structure +$ flock -s /sys/fs/resctrl/ find /sys/fs/resctrl + +# Read directory contents and create new subdirectory + +$ cat create-dir.sh +find /sys/fs/resctrl/ > output.txt +mask = function-of(output.txt) +mkdir /sys/fs/resctrl/newres/ +echo mask > /sys/fs/resctrl/newres/schemata + +$ flock /sys/fs/resctrl/ ./create-dir.sh + +Example with C: + +/* + * Example code do take advisory locks + * before accessing resctrl filesystem + */ +#include <sys/file.h> +#include <stdlib.h> + +void resctrl_take_shared_lock(int fd) +{ + int ret; + + /* take shared lock on resctrl filesystem */ + ret = flock(fd, LOCK_SH); + if (ret) { + perror("flock"); + exit(-1); + } +} + +void resctrl_take_exclusive_lock(int fd) +{ + int ret; + + /* release lock on resctrl filesystem */ + ret = flock(fd, LOCK_EX); + if (ret) { + perror("flock"); + exit(-1); + } +} + +void resctrl_release_lock(int fd) +{ + int ret; + + /* take shared lock on resctrl filesystem */ + ret = flock(fd, LOCK_UN); + if (ret) { + perror("flock"); + exit(-1); + } +} + +void main(void) +{ + int fd, ret; + + fd = open("/sys/fs/resctrl", O_DIRECTORY); + if (fd == -1) { + perror("open"); + exit(-1); + } + resctrl_take_shared_lock(fd); + /* code to read directory contents */ + resctrl_release_lock(fd); + + resctrl_take_exclusive_lock(fd); + /* code to read and write directory contents */ + resctrl_release_lock(fd); +} diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 8567c851172c..4261b3282ad9 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1865,14 +1865,14 @@ static void __smp_spurious_interrupt(u8 vector) "should never happen.\n", vector, smp_processor_id()); } -__visible void smp_spurious_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_spurious_interrupt(struct pt_regs *regs) { entering_irq(); __smp_spurious_interrupt(~regs->orig_ax); exiting_irq(); } -__visible void smp_trace_spurious_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_trace_spurious_interrupt(struct pt_regs *regs) { u8 vector = ~regs->orig_ax; @@ -1923,14 +1923,14 @@ static void __smp_error_interrupt(struct pt_regs *regs) } -__visible void smp_error_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_error_interrupt(struct pt_regs *regs) { entering_irq(); __smp_error_interrupt(regs); exiting_irq(); } -__visible void smp_trace_error_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_trace_error_interrupt(struct pt_regs *regs) { entering_irq(); trace_error_apic_entry(ERROR_APIC_VECTOR); diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c index 5d30c5e42bb1..f3557a1eb562 100644 --- a/arch/x86/kernel/apic/vector.c +++ b/arch/x86/kernel/apic/vector.c @@ -559,7 +559,7 @@ void send_cleanup_vector(struct irq_cfg *cfg) __send_cleanup_vector(data); } -asmlinkage __visible void smp_irq_move_cleanup_interrupt(void) +asmlinkage __visible void __irq_entry smp_irq_move_cleanup_interrupt(void) { unsigned vector, me; diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c index 9e5427df3243..524cc5780a77 100644 --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c @@ -816,14 +816,14 @@ static inline void __smp_deferred_error_interrupt(void) deferred_error_int_vector(); } -asmlinkage __visible void smp_deferred_error_interrupt(void) +asmlinkage __visible void __irq_entry smp_deferred_error_interrupt(void) { entering_irq(); __smp_deferred_error_interrupt(); exiting_ack_irq(); } -asmlinkage __visible void smp_trace_deferred_error_interrupt(void) +asmlinkage __visible void __irq_entry smp_trace_deferred_error_interrupt(void) { entering_irq(); trace_deferred_error_apic_entry(DEFERRED_ERROR_VECTOR); diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c index 85469f84c921..d7cc190ae457 100644 --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c @@ -396,14 +396,16 @@ static inline void __smp_thermal_interrupt(void) smp_thermal_vector(); } -asmlinkage __visible void smp_thermal_interrupt(struct pt_regs *regs) +asmlinkage __visible void __irq_entry +smp_thermal_interrupt(struct pt_regs *regs) { entering_irq(); __smp_thermal_interrupt(); exiting_ack_irq(); } -asmlinkage __visible void smp_trace_thermal_interrupt(struct pt_regs *regs) +asmlinkage __visible void __irq_entry +smp_trace_thermal_interrupt(struct pt_regs *regs) { entering_irq(); trace_thermal_apic_entry(THERMAL_APIC_VECTOR); diff --git a/arch/x86/kernel/cpu/mcheck/threshold.c b/arch/x86/kernel/cpu/mcheck/threshold.c index 9beb092d68a5..bb0e75eed10a 100644 --- a/arch/x86/kernel/cpu/mcheck/threshold.c +++ b/arch/x86/kernel/cpu/mcheck/threshold.c @@ -23,14 +23,14 @@ static inline void __smp_threshold_interrupt(void) mce_threshold_vector(); } -asmlinkage __visible void smp_threshold_interrupt(void) +asmlinkage __visible void __irq_entry smp_threshold_interrupt(void) { entering_irq(); __smp_threshold_interrupt(); exiting_ack_irq(); } -asmlinkage __visible void smp_trace_threshold_interrupt(void) +asmlinkage __visible void __irq_entry smp_trace_threshold_interrupt(void) { entering_irq(); trace_threshold_apic_entry(THRESHOLD_APIC_VECTOR); diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 7c6e9ffe4424..4d8183b5f113 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -264,7 +264,7 @@ void __smp_x86_platform_ipi(void) x86_platform_ipi_callback(); } -__visible void smp_x86_platform_ipi(struct pt_regs *regs) +__visible void __irq_entry smp_x86_platform_ipi(struct pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs(regs); @@ -315,7 +315,7 @@ __visible void smp_kvm_posted_intr_wakeup_ipi(struct pt_regs *regs) } #endif -__visible void smp_trace_x86_platform_ipi(struct pt_regs *regs) +__visible void __irq_entry smp_trace_x86_platform_ipi(struct pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs(regs); diff --git a/arch/x86/kernel/irq_work.c b/arch/x86/kernel/irq_work.c index 3512ba607361..275487872be2 100644 --- a/arch/x86/kernel/irq_work.c +++ b/arch/x86/kernel/irq_work.c @@ -9,6 +9,7 @@ #include <linux/hardirq.h> #include <asm/apic.h> #include <asm/trace/irq_vectors.h> +#include <linux/interrupt.h> static inline void __smp_irq_work_interrupt(void) { @@ -16,14 +17,14 @@ static inline void __smp_irq_work_interrupt(void) irq_work_run(); } -__visible void smp_irq_work_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_irq_work_interrupt(struct pt_regs *regs) { ipi_entering_ack_irq(); __smp_irq_work_interrupt(); exiting_irq(); } -__visible void smp_trace_irq_work_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_trace_irq_work_interrupt(struct pt_regs *regs) { ipi_entering_ack_irq(); trace_irq_work_entry(IRQ_WORK_VECTOR); diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 69780edf0dde..4bf0c8926a1c 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -575,7 +575,9 @@ static void __init reserve_crashkernel(void) /* 0 means: find the address automatically */ if (crash_base <= 0) { /* - * kexec want bzImage is below CRASH_KERNEL_ADDR_MAX + * Set CRASH_ADDR_LOW_MAX upper bound for crash memory, + * as old kexec-tools loads bzImage below that, unless + * "crashkernel=size[KMG],high" is specified. */ crash_base = memblock_find_in_range(CRASH_ALIGN, high ? CRASH_ADDR_HIGH_MAX diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index 68f8cc222f25..d3c66a15bbde 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -259,7 +259,7 @@ static inline void __smp_reschedule_interrupt(void) scheduler_ipi(); } -__visible void smp_reschedule_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_reschedule_interrupt(struct pt_regs *regs) { ack_APIC_irq(); __smp_reschedule_interrupt(); @@ -268,7 +268,7 @@ __visible void smp_reschedule_interrupt(struct pt_regs *regs) */ } -__visible void smp_trace_reschedule_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_trace_reschedule_interrupt(struct pt_regs *regs) { /* * Need to call irq_enter() before calling the trace point. @@ -292,14 +292,15 @@ static inline void __smp_call_function_interrupt(void) inc_irq_stat(irq_call_count); } -__visible void smp_call_function_interrupt(struct pt_regs *regs) +__visible void __irq_entry smp_call_function_interrupt(struct pt_regs *regs) { ipi_entering_ack_irq(); __smp_call_function_interrupt(); exiting_irq(); } -__visible void smp_trace_call_function_interrupt(struct pt_regs *regs) +__visible void __irq_entry +smp_trace_call_function_interrupt(struct pt_regs *regs) { ipi_entering_ack_irq(); trace_call_function_entry(CALL_FUNCTION_VECTOR); @@ -314,14 +315,16 @@ static inline void __smp_call_function_single_interrupt(void) inc_irq_stat(irq_call_count); } -__visible void smp_call_function_single_interrupt(struct pt_regs *regs) +__visible void __irq_entry +smp_call_function_single_interrupt(struct pt_regs *regs) { ipi_entering_ack_irq(); __smp_call_function_single_interrupt(); exiting_irq(); } -__visible void smp_trace_call_function_single_interrupt(struct pt_regs *regs) +__visible void __irq_entry +smp_trace_call_function_single_interrupt(struct pt_regs *regs) { ipi_entering_ack_irq(); trace_call_function_single_entry(CALL_FUNCTION_SINGLE_VECTOR); |