Re: [PATCH 14/15] MIPS: csrc-sb1250: Implement read_sched_clock

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Thank you Maciej for the review!


On 03/06/2015 04:47 AM, Maciej W. Rozycki wrote:
On Wed, 4 Mar 2015, Deng-Cheng Zhu wrote:

Use sb1250 hpt for sched_clock source. This implementation will give high
resolution cputime accounting.

Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@xxxxxxxxxx>
---
  arch/mips/kernel/csrc-sb1250.c | 8 ++++++++
  1 file changed, 8 insertions(+)

diff --git a/arch/mips/kernel/csrc-sb1250.c b/arch/mips/kernel/csrc-sb1250.c
index df84836..6546fff 100644
--- a/arch/mips/kernel/csrc-sb1250.c
+++ b/arch/mips/kernel/csrc-sb1250.c
@@ -12,6 +12,7 @@
   * GNU General Public License for more details.
   */
  #include <linux/clocksource.h>
+#include <linux/sched_clock.h>
#include <asm/addrspace.h>
  #include <asm/io.h>
@@ -46,6 +47,11 @@ struct clocksource bcm1250_clocksource = {
  	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
  };
+static u64 notrace sb1250_read_sched_clock(void)
+{
+	return sb1250_hpt_read(NULL);
+}
+
  I think you're abusing the API of `sb1250_hpt_read' here, by relying on
the implementation not using its `cs' argument.

  I think it would make sense to reverse the implementation, by calling
`sb1250_read_sched_clock' from `sb1250_hpt_read' instead.  Or perhaps
better yet use a static inline helper for both, so as to avoid the extra
tail call and the associated performance hit.

   Maciej

Good point. Will do in v2.


Deng-Cheng








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