diff mbox series

[5/5] arm64: perf: Add cap_user_time_short

Message ID 20200512124451.061059334@infradead.org (mailing list archive)
State New, archived
Headers show
Series arm64: perf: Proper cap_user_time* support | expand

Commit Message

Peter Zijlstra May 12, 2020, 12:41 p.m. UTC
This completes the ARM64 cap_user_time support.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/arm64/kernel/perf_event.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Comments

Leo Yan May 12, 2020, 2:11 p.m. UTC | #1
On Tue, May 12, 2020 at 02:41:03PM +0200, Peter Zijlstra wrote:
> This completes the ARM64 cap_user_time support.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
>  arch/arm64/kernel/perf_event.c |   12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> --- a/arch/arm64/kernel/perf_event.c
> +++ b/arch/arm64/kernel/perf_event.c
> @@ -1173,6 +1173,7 @@ void arch_perf_update_userpage(struct pe
>  
>  	userpg->cap_user_time = 0;
>  	userpg->cap_user_time_zero = 0;
> +	userpg->cap_user_time_short = 0;
>  
>  	do {
>  		rd = sched_clock_read_begin(&seq);
> @@ -1183,13 +1184,13 @@ void arch_perf_update_userpage(struct pe
>  		userpg->time_mult = rd->mult;
>  		userpg->time_shift = rd->shift;
>  		userpg->time_zero = rd->epoch_ns;
> +		userpg->time_cycle = rd->epoch_cyc;

s/time_cycle/time_cycles, maybe consider to change the naming to
'time_cycle'.

This patch set looks good to me after I tested it on Arm64 board.

Thanks,
Leo

> +		userpg->time_mask = rd->sched_clock_mask;
>  
>  		/*
> -		 * This isn't strictly correct, the ARM64 counter can be
> -		 * 'short' and then we get funnies when it wraps. The correct
> -		 * thing would be to extend the perf ABI with a cycle and mask
> -		 * value, but because wrapping on ARM64 is very rare in
> -		 * practise this 'works'.
> +		 * Subtract the cycle base, such that software that
> +		 * doesn't know about cap_user_time_short still 'works'
> +		 * assuming no wraps.
>  		 */
>  		userpg->time_zero -= (rd->epoch_cyc * rd->mult) >> rd->shift;
>  
> @@ -1214,4 +1215,5 @@ void arch_perf_update_userpage(struct pe
>  	 */
>  	userpg->cap_user_time = 1;
>  	userpg->cap_user_time_zero = 1;
> +	userpg->cap_user_time_short = 1;
>  }
> 
>
kernel test robot May 12, 2020, 4:59 p.m. UTC | #2
Hi Peter,

I love your patch! Yet something to improve:

[auto build test ERROR on tip/perf/core]
[also build test ERROR on arm64/for-next/core arm-perf/for-next/perf linus/master v5.7-rc5 next-20200512]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Peter-Zijlstra/arm64-perf-Proper-cap_user_time-support/20200512-205141
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 059c6d68cfc5f85ba3ab71d71a6de380016f7936
config: arm64-allyesconfig (attached as .config)
compiler: aarch64-linux-gcc (GCC) 9.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross ARCH=arm64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

arch/arm64/kernel/perf_event.c: In function 'arch_perf_update_userpage':
>> arch/arm64/kernel/perf_event.c:1187:11: error: 'struct perf_event_mmap_page' has no member named 'time_cycle'; did you mean 'time_cycles'?
1187 |   userpg->time_cycle = rd->epoch_cyc;
|           ^~~~~~~~~~
|           time_cycles
arch/arm64/kernel/perf_event.c:1207:12: error: 'struct perf_event_mmap_page' has no member named 'shift'
1207 |  if (userpg->shift == 32) {
|            ^~
arch/arm64/kernel/perf_event.c:1208:9: error: 'struct perf_event_mmap_page' has no member named 'shift'
1208 |   userpg->shift = 31;
|         ^~

vim +1187 arch/arm64/kernel/perf_event.c

  1167	
  1168	void arch_perf_update_userpage(struct perf_event *event,
  1169				       struct perf_event_mmap_page *userpg, u64 now)
  1170	{
  1171		struct clock_read_data *rd;
  1172		unsigned int seq;
  1173	
  1174		userpg->cap_user_time = 0;
  1175		userpg->cap_user_time_zero = 0;
  1176		userpg->cap_user_time_short = 0;
  1177	
  1178		do {
  1179			rd = sched_clock_read_begin(&seq);
  1180	
  1181			if (rd->read_sched_clock != arch_timer_read_counter)
  1182				return;
  1183	
  1184			userpg->time_mult = rd->mult;
  1185			userpg->time_shift = rd->shift;
  1186			userpg->time_zero = rd->epoch_ns;
> 1187			userpg->time_cycle = rd->epoch_cyc;

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1173,6 +1173,7 @@  void arch_perf_update_userpage(struct pe
 
 	userpg->cap_user_time = 0;
 	userpg->cap_user_time_zero = 0;
+	userpg->cap_user_time_short = 0;
 
 	do {
 		rd = sched_clock_read_begin(&seq);
@@ -1183,13 +1184,13 @@  void arch_perf_update_userpage(struct pe
 		userpg->time_mult = rd->mult;
 		userpg->time_shift = rd->shift;
 		userpg->time_zero = rd->epoch_ns;
+		userpg->time_cycle = rd->epoch_cyc;
+		userpg->time_mask = rd->sched_clock_mask;
 
 		/*
-		 * This isn't strictly correct, the ARM64 counter can be
-		 * 'short' and then we get funnies when it wraps. The correct
-		 * thing would be to extend the perf ABI with a cycle and mask
-		 * value, but because wrapping on ARM64 is very rare in
-		 * practise this 'works'.
+		 * Subtract the cycle base, such that software that
+		 * doesn't know about cap_user_time_short still 'works'
+		 * assuming no wraps.
 		 */
 		userpg->time_zero -= (rd->epoch_cyc * rd->mult) >> rd->shift;
 
@@ -1214,4 +1215,5 @@  void arch_perf_update_userpage(struct pe
 	 */
 	userpg->cap_user_time = 1;
 	userpg->cap_user_time_zero = 1;
+	userpg->cap_user_time_short = 1;
 }