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The nmi parameter indicated if we could do wakeups from the current
context, if not, we would set some state and self-IPI and let the
resulting interrupt do the wakeup.
For the various event classes:
- hardware: nmi=0; PMI is in fact an NMI or we run irq_work_run from
the PMI-tail (ARM etc.)
- tracepoint: nmi=0; since tracepoint could be from NMI context.
- software: nmi=[0,1]; some, like the schedule thing cannot
perform wakeups, and hence need 0.
As one can see, there is very little nmi=1 usage, and the down-side of
not using it is that on some platforms some software events can have a
jiffy delay in wakeup (when arch_irq_work_raise isn't implemented).
The up-side however is that we can remove the nmi parameter and save a
bunch of conditionals in fast paths.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Michael Cree <mcree@orcon.net.nz>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/n/tip-agjev8eu666tvknpb3iaj0fg@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
97 lines
2.3 KiB
C
97 lines
2.3 KiB
C
#ifndef _KERNEL_EVENTS_INTERNAL_H
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#define _KERNEL_EVENTS_INTERNAL_H
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#define RING_BUFFER_WRITABLE 0x01
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struct ring_buffer {
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atomic_t refcount;
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struct rcu_head rcu_head;
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#ifdef CONFIG_PERF_USE_VMALLOC
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struct work_struct work;
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int page_order; /* allocation order */
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#endif
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int nr_pages; /* nr of data pages */
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int writable; /* are we writable */
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atomic_t poll; /* POLL_ for wakeups */
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local_t head; /* write position */
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local_t nest; /* nested writers */
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local_t events; /* event limit */
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local_t wakeup; /* wakeup stamp */
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local_t lost; /* nr records lost */
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long watermark; /* wakeup watermark */
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struct perf_event_mmap_page *user_page;
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void *data_pages[0];
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};
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extern void rb_free(struct ring_buffer *rb);
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extern struct ring_buffer *
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rb_alloc(int nr_pages, long watermark, int cpu, int flags);
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extern void perf_event_wakeup(struct perf_event *event);
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extern void
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perf_event_header__init_id(struct perf_event_header *header,
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struct perf_sample_data *data,
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struct perf_event *event);
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extern void
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perf_event__output_id_sample(struct perf_event *event,
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struct perf_output_handle *handle,
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struct perf_sample_data *sample);
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extern struct page *
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perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff);
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#ifdef CONFIG_PERF_USE_VMALLOC
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/*
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* Back perf_mmap() with vmalloc memory.
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*
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* Required for architectures that have d-cache aliasing issues.
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*/
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static inline int page_order(struct ring_buffer *rb)
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{
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return rb->page_order;
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}
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#else
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static inline int page_order(struct ring_buffer *rb)
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{
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return 0;
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}
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#endif
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static unsigned long perf_data_size(struct ring_buffer *rb)
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{
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return rb->nr_pages << (PAGE_SHIFT + page_order(rb));
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}
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static inline void
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__output_copy(struct perf_output_handle *handle,
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const void *buf, unsigned int len)
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{
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do {
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unsigned long size = min_t(unsigned long, handle->size, len);
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memcpy(handle->addr, buf, size);
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len -= size;
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handle->addr += size;
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buf += size;
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handle->size -= size;
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if (!handle->size) {
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struct ring_buffer *rb = handle->rb;
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handle->page++;
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handle->page &= rb->nr_pages - 1;
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handle->addr = rb->data_pages[handle->page];
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handle->size = PAGE_SIZE << page_order(rb);
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}
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} while (len);
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}
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#endif /* _KERNEL_EVENTS_INTERNAL_H */
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