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Commit 5855fead authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
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ftrace: Use bsearch to find record ip 



Now that each set of pages in the function list are sorted by
ip, we can use bsearch to find a record within each set of pages.
This speeds up the ftrace_location() function by magnitudes.

For archs (like x86) that need to add a breakpoint at every function
that will be converted from a nop to a callback and vice versa,
the breakpoint callback needs to know if the breakpoint was for
ftrace or not. It requires finding the breakpoint ip within the
records. Doing a linear search is extremely inefficient. It is
a must to be able to do a fast binary search to find these locations.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 68950619

kernel/trace/ftrace.c

+23 −15
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/hardirq.h>

#include <linux/kthread.h>

#include <linux/uaccess.h>

#include <linux/bsearch.h>

#include <linux/module.h>

#include <linux/ftrace.h>

#include <linux/sysctl.h>
@@ -1300,6 +1301,19 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip) 
		}				\

	}





static int ftrace_cmp_recs(const void *a, const void *b)

{

	const struct dyn_ftrace *reca = a;

	const struct dyn_ftrace *recb = b;



	if (reca->ip > recb->ip)

		return 1;

	if (reca->ip < recb->ip)

		return -1;

	return 0;

}



/**

 * ftrace_location - return true if the ip giving is a traced location

 * @ip: the instruction pointer to check
@@ -1313,11 +1327,17 @@ int ftrace_location(unsigned long ip) 
{

	struct ftrace_page *pg;

	struct dyn_ftrace *rec;

	struct dyn_ftrace key;



	do_for_each_ftrace_rec(pg, rec) {

		if (rec->ip == ip)

	key.ip = ip;



	for (pg = ftrace_pages_start; pg; pg = pg->next) {

		rec = bsearch(&key, pg->records, pg->index,

			      sizeof(struct dyn_ftrace),

			      ftrace_cmp_recs);

		if (rec)

			return 1;

	} while_for_each_ftrace_rec();

	}



	return 0;

}
@@ -3587,18 +3607,6 @@ static void ftrace_swap_recs(void *a, void *b, int size) 
	*recb = t;

}



static int ftrace_cmp_recs(const void *a, const void *b)

{

	const struct dyn_ftrace *reca = a;

	const struct dyn_ftrace *recb = b;



	if (reca->ip > recb->ip)

		return 1;

	if (reca->ip < recb->ip)

		return -1;

	return 0;

}



static int ftrace_process_locs(struct module *mod,

			       unsigned long *start,

			       unsigned long *end)