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ftrace: Sort all function addresses, not just per page
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Instead of just sorting the ip's of the functions per ftrace page,
sort the entire list before adding them to the ftrace pages.

This will allow the bsearch algorithm to be sped up as it can
also sort by pages, not just records within a page.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Steven Rostedt authored and Steven Rostedt committed May 16, 2012
1 parent 71babb2 commit 9fd4932
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Showing 2 changed files with 23 additions and 13 deletions.
2 changes: 1 addition & 1 deletion include/asm-generic/vmlinux.lds.h
Original file line number Diff line number Diff line change
Expand Up @@ -486,8 +486,8 @@
CPU_DISCARD(init.data) \
MEM_DISCARD(init.data) \
KERNEL_CTORS() \
*(.init.rodata) \
MCOUNT_REC() \
*(.init.rodata) \
FTRACE_EVENTS() \
TRACE_SYSCALLS() \
DEV_DISCARD(init.rodata) \
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34 changes: 22 additions & 12 deletions kernel/trace/ftrace.c
Original file line number Diff line number Diff line change
Expand Up @@ -3666,15 +3666,27 @@ static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
return 0;
}

static void ftrace_swap_recs(void *a, void *b, int size)
static int ftrace_cmp_ips(const void *a, const void *b)
{
struct dyn_ftrace *reca = a;
struct dyn_ftrace *recb = b;
struct dyn_ftrace t;
const unsigned long *ipa = a;
const unsigned long *ipb = b;

t = *reca;
*reca = *recb;
*recb = t;
if (*ipa > *ipb)
return 1;
if (*ipa < *ipb)
return -1;
return 0;
}

static void ftrace_swap_ips(void *a, void *b, int size)
{
unsigned long *ipa = a;
unsigned long *ipb = b;
unsigned long t;

t = *ipa;
*ipa = *ipb;
*ipb = t;
}

static int ftrace_process_locs(struct module *mod,
Expand All @@ -3693,6 +3705,9 @@ static int ftrace_process_locs(struct module *mod,
if (!count)
return 0;

sort(start, count, sizeof(*start),
ftrace_cmp_ips, ftrace_swap_ips);

pg = ftrace_allocate_pages(count);
if (!pg)
return -ENOMEM;
Expand Down Expand Up @@ -3740,11 +3755,6 @@ static int ftrace_process_locs(struct module *mod,
/* These new locations need to be initialized */
ftrace_new_pgs = pg;

/* Make each individual set of pages sorted by ips */
for (; pg; pg = pg->next)
sort(pg->records, pg->index, sizeof(struct dyn_ftrace),
ftrace_cmp_recs, ftrace_swap_recs);

/*
* We only need to disable interrupts on start up
* because we are modifying code that an interrupt
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