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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: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2011-12-16 19:27:42 -05:00 committed by Steven Rostedt
parent 68950619f8
commit 5855fead9c
1 changed files with 23 additions and 15 deletions
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38
kernel/trace/ftrace.c
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@ -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)