+Honza and Nathan.
David
On Thu, May 3, 2012 at 10:52 AM, Teresa Johnson <tejohn...@google.com> wrote:
> This patch adds functionality to libgcov to enable user applications to
> collect profile data only in regions of interest. This is useful, for
> example, to collect profile data from a long-running server only
> during the time when it is serving requests.
>
> Specifically, the new routines __gcov_reset will clear all profile counters
> to zero and __gcov_dump will write out the profile information collected so
> far. A global variable is used to prevent writing out the profile a
> second time during exit.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu. Is this ok for trunk?
>
> Thanks,
> Teresa
>
> 2012-05-03 Teresa Johnson <tejohn...@google.com>
>
> * libgcc/libgcov.c (gcov_clear, __gcov_reset): New functions.
> (__gcov_dump): Ditto.
> (gcov_dump_complete): New global variable.
> (__gcov_flush): Outline functionality now in gcov_clear.
> * gcc/gcov-io.h (__gcov_reset, __gcov_dump): Declare.
>
> Index: libgcc/libgcov.c
> ===================================================================
> --- libgcc/libgcov.c (revision 187048)
> +++ libgcc/libgcov.c (working copy)
> @@ -48,6 +48,8 @@ see the files COPYING3 and COPYING.RUNTIME respect
> #ifdef L_gcov
> void __gcov_init (struct gcov_info *p __attribute__ ((unused))) {}
> void __gcov_flush (void) {}
> +void __gcov_reset (void) {}
> +void __gcov_dump (void) {}
> #endif
>
> #ifdef L_gcov_merge_add
> @@ -91,6 +93,9 @@ static struct gcov_info *gcov_list;
> /* Size of the longest file name. */
> static size_t gcov_max_filename = 0;
>
> +/* Flag when the profile has already been dumped via __gcov_dump(). */
> +static int gcov_dump_complete = 0;
> +
> /* Make sure path component of the given FILENAME exists, create
> missing directories. FILENAME must be writable.
> Returns zero on success, or -1 if an error occurred. */
> @@ -286,6 +291,11 @@ gcov_exit (void)
> char *gi_filename, *gi_filename_up;
> gcov_unsigned_t crc32 = 0;
>
> + /* Prevent the counters from being dumped a second time on exit when the
> + application already wrote out the profile using __gcov_dump(). */
> + if (gcov_dump_complete)
> + return;
> +
> memset (&all_prg, 0, sizeof (all_prg));
> /* Find the totals for this execution. */
> memset (&this_prg, 0, sizeof (this_prg));
> @@ -679,6 +689,37 @@ gcov_exit (void)
> }
> }
>
> +/* Reset all counters to zero. */
> +
> +static void
> +gcov_clear (void)
> +{
> + const struct gcov_info *gi_ptr;
> +
> + for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
> + {
> + unsigned f_ix;
> +
> + for (f_ix = 0; f_ix < gi_ptr->n_functions; f_ix++)
> + {
> + unsigned t_ix;
> + const struct gcov_fn_info *gfi_ptr = gi_ptr->functions[f_ix];
> +
> + if (!gfi_ptr || gfi_ptr->key != gi_ptr)
> + continue;
> + const struct gcov_ctr_info *ci_ptr = gfi_ptr->ctrs;
> + for (t_ix = 0; t_ix != GCOV_COUNTERS; t_ix++)
> + {
> + if (!gi_ptr->merge[t_ix])
> + continue;
> +
> + memset (ci_ptr->values, 0, sizeof (gcov_type) * ci_ptr->num);
> + ci_ptr++;
> + }
> + }
> + }
> +}
> +
> /* Add a new object file onto the bb chain. Invoked automatically
> when running an object file's global ctors. */
>
> @@ -730,38 +771,38 @@ init_mx_once (void)
> void
> __gcov_flush (void)
> {
> - const struct gcov_info *gi_ptr;
> -
> init_mx_once ();
> __gthread_mutex_lock (&__gcov_flush_mx);
>
> gcov_exit ();
> - for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
> - {
> - unsigned f_ix;
> + gcov_clear ();
>
> - for (f_ix = 0; f_ix < gi_ptr->n_functions; f_ix++)
> - {
> - unsigned t_ix;
> - const struct gcov_fn_info *gfi_ptr = gi_ptr->functions[f_ix];
> + __gthread_mutex_unlock (&__gcov_flush_mx);
> +}
>
> - if (!gfi_ptr || gfi_ptr->key != gi_ptr)
> - continue;
> - const struct gcov_ctr_info *ci_ptr = gfi_ptr->ctrs;
> - for (t_ix = 0; t_ix != GCOV_COUNTERS; t_ix++)
> - {
> - if (!gi_ptr->merge[t_ix])
> - continue;
> -
> - memset (ci_ptr->values, 0, sizeof (gcov_type) * ci_ptr->num);
> - ci_ptr++;
> - }
> - }
> - }
> +/* Function that can be called from application to reset counters to zero,
> + in order to collect profile in region of interest. */
>
> - __gthread_mutex_unlock (&__gcov_flush_mx);
> +void
> +__gcov_reset (void)
> +{
> + gcov_clear ();
> + /* Re-enable dumping to support collecting profile in multiple regions
> + of interest. */
> + gcov_dump_complete = 0;
> }
>
> +/* Function that can be called from application to write profile collected
> + so far, in order to collect profile in region of interest. */
> +
> +void
> +__gcov_dump (void)
> +{
> + gcov_exit ();
> + /* Prevent profile from being dumped a second time on application exit. */
> + gcov_dump_complete = 1;
> +}
> +
> #endif /* L_gcov */
>
> #ifdef L_gcov_merge_add
> Index: gcc/gcov-io.h
> ===================================================================
> --- gcc/gcov-io.h (revision 187048)
> +++ gcc/gcov-io.h (working copy)
> @@ -458,6 +458,12 @@ extern void __gcov_init (struct gcov_info *) ATTRI
> /* Called before fork, to avoid double counting. */
> extern void __gcov_flush (void) ATTRIBUTE_HIDDEN;
>
> +/* Function to reset all counters to 0. */
> +extern void __gcov_reset (void);
> +
> +/* Function to enable early write of profile information so far. */
> +extern void __gcov_dump (void);
> +
> /* The merge function that just sums the counters. */
> extern void __gcov_merge_add (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
>
>
> --
> This patch is available for review at http://codereview.appspot.com/6186044
