ring-buffer: read page interface

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Impact: new API to ring buffer

This patch adds a new interface into the ring buffer that allows a
page to be read from the ring buffer on a given CPU. For every page
read, one must also be given to allow for a "swap" of the pages.

 rpage = ring_buffer_alloc_read_page(buffer);
 if (!rpage)
	goto err;
 ret = ring_buffer_read_page(buffer, &rpage, cpu, full);
 if (!ret)
	goto empty;
 process_page(rpage);
 ring_buffer_free_read_page(rpage);

The caller of these functions must handle any waits that are
needed to wait for new data. The ring_buffer_read_page will simply
return 0 if there is no data, or if "full" is set and the writer
is still on the current page.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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This commit is contained in:

Steven Rostedt 2008-12-02 15:34:07 -05:00 • committed by Ingo Molnar

parent abc9b56d66

commit 8789a9e7df

2 changed files with 171 additions and 0 deletions

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5

include/linux/ring_buffer.h

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166

kernel/trace/ring_buffer.c

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