diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-05-26 18:11:02 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-05-28 10:54:15 +0200 |
| commit | 4b44a21dd640b692d4e9b12d3e37c24825f90baa (patch) | |
| tree | 5dea8495f643a9152ce6ada83d8f5f6466f1d898 /include/linux | |
| parent | b2a02fc43a1f40ef4eb2fb2b06357382608d4d84 (diff) | |
irq_work, smp: Allow irq_work on call_single_queue
Currently irq_work_queue_on() will issue an unconditional
arch_send_call_function_single_ipi() and has the handler do
irq_work_run().
This is unfortunate in that it makes the IPI handler look at a second
cacheline and it misses the opportunity to avoid the IPI. Instead note
that struct irq_work and struct __call_single_data are very similar in
layout, so use a few bits in the flags word to encode a type and stick
the irq_work on the call_single_queue list.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200526161908.011635912@infradead.org
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/irq_work.h | 7 | ||||
| -rw-r--r-- | include/linux/smp.h | 23 |
2 files changed, 28 insertions, 2 deletions
diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h index 3b752e80c017..f23a359c8f46 100644 --- a/include/linux/irq_work.h +++ b/include/linux/irq_work.h @@ -13,6 +13,8 @@ * busy NULL, 2 -> {free, claimed} : callback in progress, can be claimed */ +/* flags share CSD_FLAG_ space */ + #define IRQ_WORK_PENDING BIT(0) #define IRQ_WORK_BUSY BIT(1) @@ -23,9 +25,12 @@ #define IRQ_WORK_CLAIMED (IRQ_WORK_PENDING | IRQ_WORK_BUSY) +/* + * structure shares layout with single_call_data_t. + */ struct irq_work { - atomic_t flags; struct llist_node llnode; + atomic_t flags; void (*func)(struct irq_work *); }; diff --git a/include/linux/smp.h b/include/linux/smp.h index cbc9162689d0..45ad6e30f398 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -16,17 +16,38 @@ typedef void (*smp_call_func_t)(void *info); typedef bool (*smp_cond_func_t)(int cpu, void *info); + +enum { + CSD_FLAG_LOCK = 0x01, + + /* IRQ_WORK_flags */ + + CSD_TYPE_ASYNC = 0x00, + CSD_TYPE_SYNC = 0x10, + CSD_TYPE_IRQ_WORK = 0x20, + CSD_FLAG_TYPE_MASK = 0xF0, +}; + +/* + * structure shares (partial) layout with struct irq_work + */ struct __call_single_data { struct llist_node llist; + unsigned int flags; smp_call_func_t func; void *info; - unsigned int flags; }; /* Use __aligned() to avoid to use 2 cache lines for 1 csd */ typedef struct __call_single_data call_single_data_t __aligned(sizeof(struct __call_single_data)); +/* + * Enqueue a llist_node on the call_single_queue; be very careful, read + * flush_smp_call_function_queue() in detail. + */ +extern void __smp_call_single_queue(int cpu, struct llist_node *node); + /* total number of cpus in this system (may exceed NR_CPUS) */ extern unsigned int total_cpus; |